Influence of fabrication method on the marginal fit of temporary restorations.

Computer-aided manufacturing (CAM) technology allows the use of different manufacturing techniques. This in vitro study aimed to evaluate the marginal fit of temporary restorations manufactured using conventional chairside methods, milling, and three-dimensional printing. Fifteen 3-element temporary restorations specimens were produced and categorized into three groups: non-digital, obtained using the conventional chairside method (GC); milled (GM); and three-dimensionally printed (GP). Marginal fit was assessed using scanning electron microscopy (SEM) performed under two conditions: one with only the central screw tightened, and the other with all three screws tightened. Horizontal misfit values were categorized as over-, equal-, and under-extended and qualitatively analyzed. Statistical analysis was performed using the Tukey-Kramer test (α=0.05). In the vertical assessment, three-dimensionally printed restorations demonstrated greater misfit than restorations obtained by milling and the conventional chairside method (P<0.05). In the horizontal assessment, the misfit in the GP group was significantly higher than that in the GM and GC groups. Restorations obtained using the conventional chairside method and milled provisional restorations showed more favorable results than three-dimensionally printed restorations.

Accuracy of Conventional and 3D-Printed Casts for Partial Fixed Prostheses.

PURPOSE: To evaluate and compare the accuracy of conventional and 3D-printed casts using five different 3D printers. MATERIALS AND METHODS: In the control group (CG group, n = 5), five conventional impressions using light- and heavy-body polyvinyl siloxane were obtained from the master model, resulting in five stone models. In the test groups, five different scans were performed by a well-trained and experienced clinician using a TRIOS intraoral scanner. All data were exported in STL file format, processed, and sent to five 3D printers. Five casts were manufactured in each printer group: SG (CARES P20, Straumann); FG (Form 2, Formlabs); WG (Duplicator 7, Wanhao); ZG (Zenith D, Zenith); and MG (Moonray S100, Moonray). Measurements of the accuracy (trueness and precision) of the casts obtained from conventional elastomeric impressions and 3D-printing methods were accomplished using a 3D analysis software (Geomagic Control). RESULTS: The FG group showed the lowest values for trueness (indicating a value closer to real dimensions), which were similar to the SG group only (P > .05). MG, WG, and ZG groups presented higher values and were similar compared to each other. Data on precision demonstrated that all 3D-printed groups showed lower values for precision (smaller deviation) when compared to the CG. CONCLUSIONS: The trueness depends on the chosen 3D printer. All of the tested 3D printers were more precise than cast models obtained from conventional elastomeric impressions.

Computer-Aided Design/Computer-Aided Manufacturing of Customized Abutment for Rehabilitating a Malpositioned Implant Using Digital Flow: A Case Report.

This study presented a rehabilitation option for malpositioned implants; this involved obtaining their position and inclination through intraoral scanning, and producing a customized abutment with CAD/CAM technology. The patient in this case report presented a root fracture in tooth 21 and was subjected to extraction, implant installation, and immediate provisional prosthesis. The implant was installed with a distal inclination due to anatomical limitations. After osseointegration, an intraoral scanning transfer provided a digital model (file extension .stl), which reproduced the implant's position and inclination. Then, the file was sent so that a customized abutment (CAD/CAM) could be manufactured, promoting the final rehabilitation of the case; this allowed for good hygiene, load distribution in the dynamic interocclusal relationship, and favorable esthetics, whereas many would otherwise recommend implant removal. The result presented lower costs, a shorter time frame, and a lower morbidity for the patient.

Influence of diameter on mechanical behavior of morse taper narrow implants

Dental implants could give back function, esthetics and quality of life to patients. The correct choice of the implant, especially in borderline cases, is essential for a satisfactory result. Aim: Thus, the objective of this study was to evaluate the mechanical behavior of Morse taper implants with two different prosthetic interfaces. Methods: Twenty self-locking Morse taper implants, 2.9 mm in diameter (FAC), and 20 Morse taper implants, 3.5 mm in diameter (CM) were divided into two groups (n=10), and submitted to strength to failure test, optical microscopic evaluation of fracture, metallographic analysis of the alloy, finite element analysis (FEA) and strain gauge test. A Student's t test (α = 0.05) was made for a statistical analysis. Results: For the strength to failure test, a statistically difference was observed (p <0.001) between FAC (225.0 ± 19.8 N) and CM (397.3 ± 12.5 N). The optical microscopic evaluation demonstrated a fracture pattern that corroborated with FEA ́s results. The metallographic analysis determined that the implants of the FAC group have titanium-aluminum-vanadium alloy in their composition. In the strain gauge test, there was no statistical difference (p = 0.833) between CM (1064.8 ± 575.04 µS) and FAC (1002.2 ± 657.6 µS) groups. Conclusion: Based on the results obtained in this study, ultra-narrow implants (FAC) should ideally be restricted to areas with low masticatory effort

Influence of the geometry of the screwdriver-screw connection on the reverse torque of UCLA screws.

The aim of this study was to evaluate the influence of the geometry of the screwdriver-screw connection on the reverse torque of UCLA screws after repeated cycles of tightening and loosening in an implant-supported prosthesis. Thirty sets of external hex titanium implants, UCLA abutments, and UCLA abutment screws were divided into 3 experimental groups (n = 10). In the square group, the implant and UCLA abutment system were mounted in an upright position using a screw with a square screwdriver-screw connection. In the hexagonal group, the implant and UCLA abutment system were mounted in an upright position using a screw with a hexagonal screwdriver-screw connection. In the hexalobular group, the implant and UCLA abutment system were mounted at 70° using a dynamic UCLA abutment and screw with a hexalobular screwdriver-screw connection. Ten alternating torque-reverse torque cycles were applied to each screw using a screwdriver fixed at the end of a digital torque meter. The screws with a square connection resulted in less loss of reverse torque than the other types. Screws with a hexagonal connection showed a statistically significant loss of torque initially but remained constant for the remaining cycles. For the screws with a hexalobular connection, the loss of torque was greater, and substantial deformation of the plastic in the microstructure was noted. The screwdriver-screw connection geometry had a direct influence on the reverse torque of UCLA screws, and the initial reverse torque of the abutment screws with a square connection was greater than that of the hexagonal and hexalobular designs.

Influence of operator experience, scanner type, and scan size on 3D scans.

STATEMENT OF PROBLEM: Intraoral scanners (IOSs) have some inherent distortions caused by optical and/or software imperfections. However, how other factors such as operator experience, scan time, scanner type, and scan size influence scan accuracy is not clear. PURPOSE: The purpose of this in vitro study was to evaluate the trueness and precision of scans performed by 3 professionals with different levels of experience by using 2 IOSs. MATERIAL AND METHODS: Three operators with low, medium, and high levels of experience scanned a master model 10 times by using 2 IOSs (CEREC Omnicam; Dentsply Sirona and TRIOS 3; 3Shape), resulting in 10 standard tessellation language files for each group (N=60). Each standard tessellation language file was divided into 2 areas (prepared teeth and complete arch). Precision was evaluated by comparing the 10 scans from each examiner for each system. Trueness was evaluated by comparing each scan file with a reference scan obtained from a laboratory scanner (D2000; 3Shape). A 3D analysis software program (Geomagic Control; 3D Systems) was used to perform all the comparisons and superimpositions. The 3-way ANOVA test followed by the Tukey HSD test were used to assess precision and trueness. The 2-way ANOVA followed by the Tukey HSD test was used to assess scan time. The Pearson correlation test was performed between scan time and trueness for both scanners. An additional correlation was performed between scan time and number of images, as well as between number of images and trueness for the TRIOS 3. RESULTS: Statistically significant influences of operator (P<.001), scanner (P<.001), scan size (P<.001), operator and scan size (P<.001), and scanner and scan size (P<.001) were observed. The TRIOS 3 group reported higher precision than the CEREC Omnicam group for complete-arch scans (P<.001), although no difference was observed for scans of the prepared tooth. Medium- (P=.002) and low-experience operators (P<.001) reported lower precision for complete-arch scans performed with CEREC Omnicam when compared with TRIOS 3. The low-experience operator reported significantly worse results for complete-arch scans in comparison with the medium- (P=.008 and P<.001) and high-experience operators (P<.001 and P=.001), by using TRIOS 3 and CEREC Omnicam, respectively. Medium- and high-experience operators reported similar results among themselves. The CEREC Omnicam scanner reported lower trueness for complete-arch scans when compared with the prepared tooth (P<.001); for TRIOS 3, a difference was only observed for the low-experience operator when compared with the high-experience operator (P<.001). The CEREC Omnicam reported lower trueness than the TRIOS 3, except for the medium-experience operator with the prepared tooth scan. Comparing the trueness between operators and considering the same scanner and scan size, all groups were similar. The low-experience operator had a longer scanning time than the medium- and high-experience operators. For TRIOS 3, the low-experience operator obtained the highest number of images during each scan. CONCLUSIONS: The accuracy of intraoral scans was influenced by operator experience, type of IOSs, and scan size. More experienced operators and smaller scan sizes made for more accurate scans. In addition, more experienced operators made faster scans, and the TRIOS 3 was more accurate than the CEREC Omnicam for complete-arch scans.

Effect of exposure time and moving the curing light on the degree of conversion and Knoop microhardness of light-cured resin cements.

OBJECTIVE: To evaluate the effect of exposure time and moving the light-curing unit (LCU) on the degree of conversion (DC) and Knoop microhardness (KH) of two resin cements that were light-cured through ceramic. METHODS: Two resin cements: AllCem Veneer APS (FGM) and Variolink Esthetic LC (Ivoclar Vivadent) were placed into a 0.3 mm thick matrix in 6 locations representing the canine to canine. The resins were covered with 0.5 mm thick lithium disilicate glass-ceramic (IPS e.max CAD, Ivoclar Vivadent). A motorized device moved the LCUs over the ceramic when the LCU was on. Two single-peak LCUs: Elipar DeepCure-L (3M Oral Care) and Emitter C (Schuster), and one multi-peak: Bluephase G2 (Ivoclar Vivadent) were used with 3 different exposure protocols: a localized exposure centered over each tooth for 10 or 40 s; moving the tip across the 6 teeth for a total exposure time of 10 or 40 s; and moving the tip across the 6 teeth resins for a total exposure time of 60 or 240 s. After 24 h, the DC and KH were measured on the top surfaces and the data was analyzed using three-way ANOVA and Tukey's tests (α = 0.05). RESULTS: Interposition of 0.5 mm of ceramic reduced the irradiance received by the resin by approximately 50%. The 40 s localized exposure over each tooth always produced significantly higher DC and KH values. Moving the LCUs with a total exposure time of 10 s resulted in the lowest DC and KH. There was no beneficial effect on the DC or KH when the multi-peak (violet-blue) LCU (Elipar DeepCure-L or Bluephase G2), but the lower light output from a small tip LCU reduced the DC and KH values (Emitter C). SIGNIFICANCE: Moving the LCUs when photo-curing light-cured resin cements is not recommended. This study showed that a single-peak LCU could activate a resin cement that uses Ivocerin™ as well as the multi-peak LCU.

Microstructural and mechanical analysis of two CAD-CAM lithium disilicate glass-reinforced ceramics.

The aim of this study was to analyze the structural, morphological and mechanical properties of two different lithium disilicate glass-reinforced ceramics for CAD-CAM systems (IPS e.max CAD and Rosetta SM). Five methodologies were used for both ceramics: microstructure (n = 2) was analyzed using x-ray diffraction (XRD); morphological properties (n = 2) were analyzed by scanning electron microscopy (SEM), with and without hydrofluoric etching; porosity (n = 3) was assessed using 3D micro-computed tomography (micro-CT); flexural strength was measured (n =1 0) using the three-point bending test; and bond strength was determined with self-adhesive resin cement (n = 10), using a microshear bond test. After performing all the tests, the data were analyzed using t-Student test and two-way ANOVA. All the tests used a significance level of α = 0.05. High peak positions corresponding to standard lithium metasilicate and lithium disilicate with similar intensities were observed for both ceramics in the XRD analysis. Morphological analysis showed that the crystalline structure of the two ceramics studied showed no statistical difference after acid etching. Additionally, no significant differences were recorded in the number or size of the pores for the ceramics evaluated. Moreover, no differences in flexural strength were found for the ceramic materials tested, or in the bond strength to ceramic substrates for the resin cements. Based on the study results, no significant differences were found between the two CAD-CAM lithium disilicate glass-reinforced ceramics tested, since they presented similar crystalline structures with comparable intensities, and similar total porosity, flexural strength and bond strength.

Microstructural and mechanical analysis of two CAD-CAM lithium disilicate glass-reinforced ceramics

Abstract The aim of this study was to analyze the structural, morphological and mechanical properties of two different lithium disilicate glass-reinforced ceramics for CAD-CAM systems (IPS e.max CAD and Rosetta SM). Five methodologies were used for both ceramics: microstructure (n = 2) was analyzed using x-ray diffraction (XRD); morphological properties (n = 2) were analyzed by scanning electron microscopy (SEM), with and without hydrofluoric etching; porosity (n = 3) was assessed using 3D micro-computed tomography (micro-CT); flexural strength was measured (n =1 0) using the three-point bending test; and bond strength was determined with self-adhesive resin cement (n = 10), using a microshear bond test. After performing all the tests, the data were analyzed using t-Student test and two-way ANOVA. All the tests used a significance level of α = 0.05. High peak positions corresponding to standard lithium metasilicate and lithium disilicate with similar intensities were observed for both ceramics in the XRD analysis. Morphological analysis showed that the crystalline structure of the two ceramics studied showed no statistical difference after acid etching. Additionally, no significant differences were recorded in the number or size of the pores for the ceramics evaluated. Moreover, no differences in flexural strength were found for the ceramic materials tested, or in the bond strength to ceramic substrates for the resin cements. Based on the study results, no significant differences were found between the two CAD-CAM lithium disilicate glass-reinforced ceramics tested, since they presented similar crystalline structures with comparable intensities, and similar total porosity, flexural strength and bond strength.

Biomechanical behavior of extra-narrow implants after fatigue and pull-out tests.

STATEMENT OF PROBLEM: Narrow implants have limited indications, and implant fracture may occur when these indications are not followed. PURPOSE: The purpose of this in vitro study was to investigate the mechanical behavior of a 2.9-mm-diameter implant using a fatigue limit test and to investigate the Morse effect of 2 different Morse taper systems, 2.9-mm-diameter (FAC group) and 3.75-mm-diameter (CM group) implants, using a pull-out test. The null hypothesis was that the tensile strengths of the components for both systems would be similar. MATERIAL AND METHODS: The fatigue properties of 13 specimens under 6 loads were determined. The test was performed at 15 Hz and for 5×106 cycles. In the pull-out test, the specimens were divided into 2 groups (n=8), the FAC group (2.9-mm-diameter) and the CM group (3.75-mm-diameter). Statistical analysis for the pull-out test was performed with the Student t test (α=.05). RESULTS: Thirteen specimens underwent the fatigue test. Only 5 did not fail when subjected to the frequency and number of cycles examined. Three of the specimens did not fail under a load of 130 N. The pull-out test showed a significant difference between the FAC and CM groups (P<.001). CONCLUSIONS: According to the fatigue test, the extra-narrow implant (Facility; Neodent) was compatible with the low masticatory effort regions, as indicated by the manufacturer. The better performance of the FAC group in the pull-out test may be due to its design, which promotes the pure Morse effect in the implant-abutment interface, and the angulation of its internal conical portion.

Influence of furnace type in the crystallization of lithium disilicate on bond strength and flexural strength

Aim: The crystallization step is required for lithium disilicate ceramics to change color, improve the mechanical properties and yield material to support mouth loading. Several furnaces could complete the crystallization process. This study evaluated the flexural and bond strength of lithium disilicate ceramics crystallized by different furnaces with the presence or not of vacum and different holding time. Methods: Forty lithium disilicate samples were divided into two groups: Programat P300 - control group with vacuum and holding time 7 minutes (CG) and FVPlus- experimental group and without vacuum and holding time 25 minutes (EG) and submitted to 2 experimental tests: 3-point flexural strength test and micro shear bond strength test (µSBS). For this test, the surface of the samples was treated and 1mm² of resin cement was applied on the surface. The samples were stored in artificial saliva over 2 time periods (24 hours: T0; 1-month storage: T1). To analyze the morphologic crystals of the ceramics tested, one representative specimen from each group were analyzed by using Scanning Electron Microscopy (SEM). Results: There was no significant difference in 3-point flexural strength test between groups CG and EG (p= 0.984). The µSBS results showed no statistical difference between groups, considering different storage time. There was no difference in the 3-point flexural strength and µSBS for lithium disilicate samples regardless of heat treatment of furnace type. The storage time had no influence on the µSBS. No differences were noted in the shape and size of these crystals when comparing the furnace analyzed by SEM images. Conclusion: Different furnaces did not influence the flexural and bond strength of lithium disilicate ceramics

Avaliação da higiene oral em prótese fixa múltipla sobre implantes expostos após necrose óssea ­ relato de caso / Evaluation of oral hygiene in multiple fixed prostheses on implants exposed after bone necrosis ­ case report

Alguns pacientes podem apresentar dificuldades motoras que inviabilizam a adequada higienização de próteses implantossuportadas. No entanto, a utilização de escovas elétricas pode compensar essas dificuldades e melhorar a qualidade de higiene oral. O presente trabalho relata um caso clínico que utilizou escova dental elétrica Philips Sonicar e AirFloss Ultra® como meio de higienização da área de implante osseointegrado exposta pós necrose óssea. Paciente dirigiu-se a um serviço de reabilitação oral com desconforto em prótese implantada ferulizada de três elementos localizada no arco inferior direito. Após análise clínica e diagnóstico, o paciente foi orientado quanto as etapas do tratamento, assim como a necessidade da manutenção dos tecidos peri-implantares através de uma correta higienização. Após um ano é possível verificar uma condição satisfatória da região avaliada e maior satisfação do paciente quanto ao método de limpeza empregado. (AU).

Some patients may present motor difficulties that prevent the adequate hygiene of implanted prosthesis. However, the use of electric toothbrushes can compensate these difficulties and improve the quality of oral hygiene. The present study reported the case of a patient who used Philips Sonicar electric brush and AirFloss Ultra® to clean an osseointegrated implant area exposed after bone necrosis. Patient went to an oral rehabilitation service with discomfort in a three-element splinted implanted prosthesis area, located in the lower right arch. After clinical analysis and diagnosis, the patient was advised on the steps of treatment as well as the necessity of the maintenance of the peri-implant tissues with a correct oral hygiene. After one year, it is still possible to verify a satisfactory condition of the evaluated region and greater satisfaction of the patient regarding the cleaning method employed. (AU).

Effect of cavity preparation design and ceramic type on the stress distribution, strain and fracture resistance of CAD/CAM onlays in molars.

Objective This study aimed to evaluate the effect of the cavity preparation and ceramic type on the stress distribution, tooth strain, fracture resistance and fracture mode of human molar teeth restored with onlays. Material and Methods Forty-eight molars were divided into four groups (n=12) with assorted combinations of two study factors: BL- conventional onlay preparation with boxes made from leucite ceramic (IPS-Empress CAD, Ivoclar Vivadent); NBL- conservative onlay preparation without boxes made from leucite ceramic; BD- conventional onlay preparation with boxes made from lithium disilicate glass ceramic (IPS e.max CAD, Ivoclar Vivadent); NBL- conservative onlay preparation with boxes made from lithium disilicate glass ceramic cuspal deformation (µS) was measured at 100 N and at maximum fracture load using strain gauge. Fracture resistance (N) was measured using a compression test, and the fracture mode was recorded. Finite element analysis was used to evaluate the stress distribution by modified von Mises stress criteria. The tooth strain and fracture resistance data were analyzed using the Tukey test and two-way ANOVA, and the fracture mode was analyzed by the chi-square test (α=0.05). Results The leucite ceramic resulted in higher tooth deformation at 100 N and lower tooth deformation at the maximum fracture load than the lithium disilicate ceramic (P<0.001). The lithium disilicate ceramic exhibited higher fracture resistance than the leucite ceramic (P<0.001). The conservative onlay resulted in higher fracture strength for lithium disilicate ceramic. Finite element analysis results showed the conventional cavity preparation resulted in higher stress concentration in the ceramic restoration and remaining tooth than the conservative onlay preparation. The conservative onlays exhibited increased fracture resistance, reduced stress concentration and more favorable fracture modes. Conclusion Molars restored with lithium disilicate CAD-CAM ceramic onlays exhibited higher fracture resistance than molars restored with leucite CAD-CAM ceramic onlays.

Effect of cavity preparation design and ceramic type on the stress distribution, strain and fracture resistance of CAD/CAM onlays in molars

Abstract Objective This study aimed to evaluate the effect of the cavity preparation and ceramic type on the stress distribution, tooth strain, fracture resistance and fracture mode of human molar teeth restored with onlays. Material and Methods Forty-eight molars were divided into four groups (n=12) with assorted combinations of two study factors: BL- conventional onlay preparation with boxes made from leucite ceramic (IPS-Empress CAD, Ivoclar Vivadent); NBL- conservative onlay preparation without boxes made from leucite ceramic; BD- conventional onlay preparation with boxes made from lithium disilicate glass ceramic (IPS e.max CAD, Ivoclar Vivadent); NBL- conservative onlay preparation with boxes made from lithium disilicate glass ceramic cuspal deformation (µS) was measured at 100 N and at maximum fracture load using strain gauge. Fracture resistance (N) was measured using a compression test, and the fracture mode was recorded. Finite element analysis was used to evaluate the stress distribution by modified von Mises stress criteria. The tooth strain and fracture resistance data were analyzed using the Tukey test and two-way ANOVA, and the fracture mode was analyzed by the chi-square test (α=0.05). Results The leucite ceramic resulted in higher tooth deformation at 100 N and lower tooth deformation at the maximum fracture load than the lithium disilicate ceramic (P<0.001). The lithium disilicate ceramic exhibited higher fracture resistance than the leucite ceramic (P<0.001). The conservative onlay resulted in higher fracture strength for lithium disilicate ceramic. Finite element analysis results showed the conventional cavity preparation resulted in higher stress concentration in the ceramic restoration and remaining tooth than the conservative onlay preparation. The conservative onlays exhibited increased fracture resistance, reduced stress concentration and more favorable fracture modes. Conclusion Molars restored with lithium disilicate CAD-CAM ceramic onlays exhibited higher fracture resistance than molars restored with leucite CAD-CAM ceramic onlays.

Comparative analysis of optical microscopy, scanning electron microscopy, and micro-computed tomography on measurements

Abstract: Microscopic measurements are widely used in scientific research and the correct equipment to perform these evaluations could be critical to determine study results. Regarding microscopic measurements, three of the most used methods are: Optical Microscopy (OM), Scanning Electron Microscopy (SEM), and Micro-computed Tomography (MCT). It is important to select the best method for assessing diverse parameters, considering operational characteristics of the method, the equipment efficiency, and the machinery cost. Aim: Therefore, the main objective of this study was to define which is the most useful measurement method for assessing magnitudes below 0.4 mm. Methods: Ten dental implants, with known dimensions as defined by the manufacturer were randomly distributed. Two blinded observers assessed the distance between the second and the third screw vortex of the implants using three suggested methods. The true distance was defined to be 0.5 mm. Results: The assessed distances were: 0.597±0.007mm for OM, 0.578±0.017mm for SEM, and 0.613±0.006mm for MCT. The assessed distances were significantly different when the methods were compared (P>0.01). All measurements were into the CAD tolerances. Conclusion: It was possible to conclude that linear easurements between 595 and 605 µm could be performed by any of the described technologies (AU)

Estética e higiene em próteses do tipo protocolo superior ­ relato de caso / Aesthetics and cleansing in upper protocol-type prostheses ­ case report

Para obter estética e funcionalidade em prótese implantada, vários detalhes devem ser observados. Um detalhe importante em próteses do tipo protocolo é a presença de espaço para higienização. Este caso clínico relata um caso em que a paciente utilizava uma prótese do tipo protocolo superior e prótese parcial removível inferior Classe I de Kennedy. Contudo, a paciente estava insatisfeita com sua prótese superior em relação à estética e dificuldade para higienização. Durante a consulta para diagnóstico e planejamento esses problemas reportados pela pacientes ficaram evidentes: mal posicionamento dos dentes, falta de espaço para corredor bucal e desvio de linha média. foi proposto a paciente a confecção de novas próteses superior e inferior, que seguiram todos os passos necessários para alcançar estética e funcionalidade. A etapa de prova de dentes superiores foi realizada três vezes, até que estivesse ideal. Após a acrilização da prótese superior foram criadas pequenas canaletas para guiar a passagem do fio dental entre os implantes, facilitando o processo de higienização. Este caso clínico demonstra que todos os parâmetros necessários para a confecção de uma prótese total adequada devem ser respeitados durante a confecção de uma prótese do tipo protocolo sobre implantes. Além disso, a confecção das canaletas para higienização permite que o paciente realize esse processo de forma satisfatória, podendo aumentar o tempo de sucesso do tratamento.

To achieve good aesthetics and function in implant-supported dental prosthesis several details must be observed. One important detail for protocol-type prosthesis is the presence of a cleansing space. This paper reports the case of a patient with upper protocol-type prosthesis and an inferior partial Kennedy Class I removable prosthesis. however, the patient was unsatisfied with the aesthetics of the upper prosthesis as well as with the difficulty of cleaning it. During consultation for diagnosis and planning the problems reported by the patient became evident: wrong positioning of the teeth, lack of buccal corridor and midline deviation. The recommendation was to manufacture new lower and upper prostheses, following all the required steps in order to achieve satisfactory aesthetics and function. for the upper teeth try-in stages were performed, until the ideal fit was reached. After acrylic cure of the upper prosthesis was performed, furrows were created in the region between the implants, serving as guide to facilitate the passage of dental floss, making it easier to clean the prosthesis. The aim of this study was to demonstrate, that all the parameters observed in the manufacture of a conventional complete denture should be followed in the confection of protocol type prosthesis. Also, the furrows allow proper hygiene, which may increase the duration of the treatment success.

Microleakage at Different Implant-Abutment Connections Under Unloaded and Loaded Conditions.

PURPOSE: This study evaluated the microleakage at different implant-abutment (I-A) connections under unloaded and loaded conditions. MATERIALS AND METHODS: Forty implants, specially designed with an opening at the apex, were grouped according to the I-A and screw device: external hexagon implants with titanium (EH) or EH diamond-like carbon screws fixing the abutment; internal hexagon implants with titanium screws (IH); and Morse taper implants with solid (MT) or MT passing screws (MTps) abutments. The implants were fixed in a 2-compartment device, and toluidine blue solution (1.0 mg/mL) was placed at the I-A interface (upper compartment). The lower compartment was filled with purified water. Four implants of each group were loaded (50 N, 1.2 Hz) and after 50,000, 100,000, 200,000, and 300,000 cycles, aliquots were collected from the lower compartment for absorbance reading. Data were analyzed using analysis of variance for repeated measurements and Tukey (α = 0.05). RESULTS: Although microleakage increased over time in most of the groups, MTps group showed lower values when loaded (P < 0.05). The DLC on the EH screw did not prevent microleakage (P < 0.05). CONCLUSION: It can be concluded that MT connection is more effective to prevent microleakage.

Influence of indexed abutments on the fracture resistance of internal conical dental implants.

The aim of this study was to evaluate the influence of abutments with a prosthetic index on the fracture resistance of Morse taper dental implants. Morse taper implants were divided into 2 groups (n = 5 per group): a group with an indexed implant and a nonindexed abutment (solid Morse taper universal post; WIS group), and a group with an indexed implant and an indexed abutment (WIP group). Both groups were subjected to bending tests for fracture strength until 5 mm of displacement or implant fracture occurred. Statistical analysis was performed using the Student t test (α = 0.05). There was no statistically significant difference between the mean fracture values, which were 305.8 N and 318.6 N for the WIS group and WIP group, respectively. The presence of a prosthetic index on Morse taper abutments did not influence the resistance to fracture.

Avaliação da eficiência antibacteriana de géis e pomadas utilizados no interior de implantes / Assessment of the efficiency of antibacterial gels and ointments used inside dental implants

Diversas substâncias antibacterianas são utilizadas nos parafusos dos componentes sobre implantes para prevenir a proliferação bacteriana no interior destes e a microinfiltração bacteriana. Este estudo tem como objetivo comparar a eficiência de diversas concentrações dos géis de clorexidina (1%, 2% e 2,5%) e tetraciclina (1%, 2% e 2,5%) e a pomada Neosporin, antibacterianos utilizados no interior de implantes. A eficiência antibacteriana foi determinada pelas zonas de inibição obtidas por meio do método de difusão em ágar, em placas previamente semeadas com Escherichia coli (ATCC 35218). O diâmetro da inibição antibacteriana foi mensurado (mm) e estatisticamente analisado (One-way ANOVA, α = 0.05). De acordo com os resultados deste estudo, os géis de tetraciclina 1%, 2% e 2,5% apresentaram maior halo inibitório, sendo estatisticamente significante, com médias de halos de 14,8 mm, 15,4 mm e 15,3 mm, respectivamente, enquanto que os géis de clorexidina 1%, 2% e 2,5% apresentaram médias de halos de 6,31 mm, 6,31 mm e 6,36 mm; a pomada de Neosporin® apresentou halo, com média de 3,28 mm, sendo os menores halos de inibição. Pode-se concluir que os géis de tetraciclina apresentam maior eficiência na atividade antibacteriana, sendo, dentre os materiais testados, o gel de tetraciclina a 1% o mais indicado para ser utilizado por não apresentar diferenças significantes em relação a outras concentrações desta substância (AU).

To prevent bacterial microleakage and growth, several antibacterial substances are randomly used inside dental implants. This study aimed to compare the efficiency of three antibacterial substances in different concentrations, used inside implants: chlorhexidine gel (1%, 2% and 2.5%) and tetracycline gel (1%, 2% and 2.5%) and Neosporin ointment. Antibacterial efficiency was determined by the diameter of inhibition zones obtained through agar diffusion method on plates previously seeded with Escherichia coli (ATCC 35218). The diameter of the antibacterial inhibition was measured (mm) and submitted to statistical analysis (One-way ANOVA, α= 0.05). According to the results of this study, statistically significant differences were observed among the substances. Tetracycline gels have presented the largest growth inhibition zones with means of 14.8 mm (1%)15.4 mm (2%) and 15.3 mm (2.5%), while chlorhexidine gel had mean zones of 6.31 mm (1%), 6.31 mm (2%) and 6.36 mm (2.5%); Neosporin® ointment had the lower zones with an average of 3.28 mm. It can be concluded that tetracycline gels are more effective against the antibacterial activity (AU).

Reabilitação maxilar após radioterapia utilizando implante unitário e prótese obturadora tipo overdenture: acompanhamento clínico de um ano / Maxillary rehabilitation after radiotherapy using a single-tooth dental implant and the obturator-type overdenture: one-year clinical follow-up

Este caso clínico relata o uso de uma prótese obturadora tipo overdenture para compensar a deficiência estética em um paciente previamente irradiado. Um indivíduo do sexo masculino, 73 anos de idade, que possuía uma prótese sobre três implantes dentários foi acometido de câncer no seio maxilar e assoalho da órbita. Seis doses de cisplatina e 35 sessões de radioterapia (dose diária 1,8 Gy) foram executadas. Após a maxilectomia, apenas um implante restou na região anterior. O tratamento consistiu de uma prótese obturadora tipo overdenture com encaixe tipo Equator. O paciente retornou um ano depois, sem alterações estéticas e com nível de satisfação melhorado. Entretanto, o anel borrachoide do encaixe foi trocado. Reabilitações implantossuportadas e mucorretidas que recebem carregamento tardio pode melhorar o prognóstico de implantes dentais em pacientes irradiados. Este cuidado mostra que este cenário ainda requer maior atenção da comunidade científica, na busca por meios de prevenir e minimizar os danos causados pela radioterapia, por inovações tecnológicas e protocolos regenerativos que potencializem a osseointegração. Com isso, a Odontologia poderá contribuir ainda mais com a melhora da qualidade de vida de pacientes, devolvendo satisfação pessoal e autoestima.

This case describes the use of an obturator-type overdenture prosthesis to compensate for the aesthetic defi ciency in a previously irradiated patient. A 73 years-old male, who had a prosthesis on three dental implants was diagnosed with cancer in the maxillary sinus and orbital floor. Six doses of cisplatin and 35 radiotherapy sessions (daily doses of 1.8 Gy) were performed. After maxillectomy, only one implant survived in the anterior region. The treatment consisted of an obturator overdenture with the Equator attachment. The patient returned one year later without cosmetic changes and demonstrated an enhanced satisfaction level. However, the o-ring rubber was replaced. Implant-supported, mucosa-retained restorations receiving delayed loading can improve the prognosis of dental implants in irradiated patients. Also, this scenario still requires more attention from the scientific community seeking for new ways to prevent and minimize damages caused by radiation, technological innovations, and regenerative protocols that enhance osseointegration. Thus, dentistry can further contribute to improving the quality of life of patients, returning their personal satisfaction and self-esteem.