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The aim was to evaluate primary implant stability and bone microarchitecture in two drilling situations, by comparing the conventional technique (CT) and osseodensification (OD) (Versah Burs - Jackson - Mississippi - USA). The implant insertion torque (IT), implant stability quotient (ISQ), and the peri-implant trabecular microstructure were assessed on bone fragments obtained from pig's tibia (n=12), divided between CT (n=6) and OD (n=6). After the drilling procedure, the implants were installed (3.5x8.5 mm, Epikut - SIN - São Paulo - Brazil). The IT and ISQ were measured using a digital torque wrench and resonance frequency analysis. Then, the bone fragments containing the implants were removed with a trephine and analyzed by Microtomography (µCT, 8.0 µm). The comparison between groups was performed using the unpaired t-test (α=0.05). The results revealed that OD promotes a higher insertion torque (CT: 7.67±2.44 Ncm; OD: 19.78±5.26 Ncm) (p=0.0005), although ISQ was not different (CT: 61.33±4.66; OD: 63.25±4.58) (p=0.48). There was a significant increase in peri-implant bone volume (CT: 23.17±3.39 mm3; OD: 32.01±5.75 mm3) (p=0.008), and trabecular parameters: separation (CT: 0.4357±0.03 mm; OD: 0.3865±0.04 mm) (p=0.0449), number (CT: 1.626±0.18 1/mm; OD: 1.946±0.13 1/mm) (p=0.007), and thickness (CT: 0.1130±0.009 mm; OD: 0.1328±0.015 mm) (p=0.02). Structure model index (SMI) data demonstrate no significant differences between groups (CT: 1.7±0.2; OD: 1.4±0.4) (p=0.12). In conclusion, OD increases the insertion torque values and promotes beneficial changes regarding bone microarchitecture compared with CT, revealing more peri-implant bone volume with consequent higher primary stability.
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Implantes Dentários , Brasil , Torque , Implantação Dentária EndósseaRESUMO
Abstract: The aim was to evaluate primary implant stability and bone microarchitecture in two drilling situations, by comparing the conventional technique (CT) and osseodensification (OD) (Versah Burs - Jackson - Mississippi - USA). The implant insertion torque (IT), implant stability quotient (ISQ), and the peri-implant trabecular microstructure were assessed on bone fragments obtained from pig's tibia (n=12), divided between CT (n=6) and OD (n=6). After the drilling procedure, the implants were installed (3.5x8.5 mm, Epikut - SIN - São Paulo - Brazil). The IT and ISQ were measured using a digital torque wrench and resonance frequency analysis. Then, the bone fragments containing the implants were removed with a trephine and analyzed by Microtomography (µCT, 8.0 µm). The comparison between groups was performed using the unpaired t-test (α=0.05). The results revealed that OD promotes a higher insertion torque (CT: 7.67±2.44 Ncm; OD: 19.78±5.26 Ncm) (p=0.0005), although ISQ was not different (CT: 61.33±4.66; OD: 63.25±4.58) (p=0.48). There was a significant increase in peri-implant bone volume (CT: 23.17±3.39 mm3; OD: 32.01±5.75 mm3) (p=0.008), and trabecular parameters: separation (CT: 0.4357±0.03 mm; OD: 0.3865±0.04 mm) (p=0.0449), number (CT: 1.626±0.18 1/mm; OD: 1.946±0.13 1/mm) (p=0.007), and thickness (CT: 0.1130±0.009 mm; OD: 0.1328±0.015 mm) (p=0.02). Structure model index (SMI) data demonstrate no significant differences between groups (CT: 1.7±0.2; OD: 1.4±0.4) (p=0.12). In conclusion, OD increases the insertion torque values and promotes beneficial changes regarding bone microarchitecture compared with CT, revealing more peri-implant bone volume with consequent higher primary stability.
Resumo O objetivo deste estudo foi avaliar a estabilidade de implante e a microarquitetura óssea em duas técnicas de fresagem, comparando a técnica convencional (CT) e a osseodensificação (OD) (Versah Burs - Jackson - Mississippi - EUA). O torque de inserção do implante (IT), quociente de estabilidade primária (ISQ) e a estrutura trabecular peri-implantar foram avaliados em fragmentos ósseos obtidos de tíbia de porco (n=12), divididos entre CT (n=6) e OD (n=6). Após o procedimento de fresagem, foram instalados implantes (3,5x8,5 mm, Epikut - SIN - São Paulo - Brasil). O IT e o ISQ foram aferidos por meio de um torquimetro digital e análise de frequência de ressonância. Em seguida, os fragmentos ósseos contendo os implantes foram removidos com trefina e analisados por microtomografia computadorizada (µCT, 8,0 µm). A comparação entre os grupos foi realizada por meio do teste-t não-pareado (α=0.05). Os resultados revelaram que a OD promove maior torque de inserção (CT: 7,67 ± 2,44º Ncm; OD: 19,78 ± 5,26 Ncm) (p=0,0005), embora a estabilidade primária não tenha sido diferente (CT: 61.33 ± 4.66; OD:63.25 ± 4.58) (p=0,48). Houve um aumento significativo no volume ósseo peri-implantar (CT: 23,17±3,39 mm3; OD: 32,01±5,75 mm3) (p=0,0089) e parâmetros trabeculares: separação (CT: 0,4357 ± 0,03 mm; OD: 0,3865 ± 0,04 mm) (p=0,0449), número (CT: 1,626 ± 0,18 1/mm; OD: 1,946 ± 0,13 1/mm) (p=0,007) e espessura (CT: 0,1130 ± 0,009 mm; OD: 0,1328 ± 0,015 mm) (p=0,02) O índice de modelo estrutural (SMI) não demostrou diferença estatisticamente significativa (p=0.1228). Concluindo, OD apresenta maiores valores de torque de inserção e promove mudanças benéficas na microarquitetura óssea em comparação com a TC, revelando maior volume ósseo peri-implantar.
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The present study evaluated the effect of the taper angle of different internal conical connection implants and cyclic loading on the implant-abutment bacterial seal. A total of 96 implant-abutment sets were divided into eight groups. Four groups of different taper degrees with cyclic mechanical loading of 500,000 cycles per sample, with a 120-N load at 2 Hz before analysis [16DC (16-degree, cycled), 11.5DC (11.5-degree, cycled), 3DC (3- degree, cycled) and 4DC (4- degree, cycled)] were compared to four control groups without cyclic loading [16D (16-degree), 11.5D (11.5-degree), 3D (3-degree), and 4D (4-degree)]. Microbiological analysis was performed by immersing all samples in a suspension containing Escherichia coli and incubating them at 37°C. After 14 days, the presence of bacterial seals was evaluated. Fisher-Freeman-Halton exact tests and binomial tests were performed (5% significance level). The groups showed significant differences in bacterial seal, and mechanical load cycling improved the bacterial seal in the 3DC group. In all other groups, no significant differences in bacterial seal were found between cycled and uncycled samples. To conclude, the internal conical connection with a 3-degree taper angle showed better results than the other connection with different angles when subjected to load cycling. However, none of the angles tested were fully effective in sealing the implant-abutment interface.
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Implantes Dentários , Implantes Dentários/microbiologia , Dente Suporte , Projeto do Implante Dentário-PivôRESUMO
Abstract The present study evaluated the effect of the taper angle of different internal conical connection implants and cyclic loading on the implant-abutment bacterial seal. A total of 96 implant-abutment sets were divided into eight groups. Four groups of different taper degrees with cyclic mechanical loading of 500,000 cycles per sample, with a 120-N load at 2 Hz before analysis [16DC (16-degree, cycled), 11.5DC (11.5-degree, cycled), 3DC (3- degree, cycled) and 4DC (4- degree, cycled)] were compared to four control groups without cyclic loading [16D (16-degree), 11.5D (11.5-degree), 3D (3-degree), and 4D (4-degree)]. Microbiological analysis was performed by immersing all samples in a suspension containing Escherichia coli and incubating them at 37°C. After 14 days, the presence of bacterial seals was evaluated. Fisher-Freeman-Halton exact tests and binomial tests were performed (5% significance level). The groups showed significant differences in bacterial seal, and mechanical load cycling improved the bacterial seal in the 3DC group. In all other groups, no significant differences in bacterial seal were found between cycled and uncycled samples. To conclude, the internal conical connection with a 3-degree taper angle showed better results than the other connection with different angles when subjected to load cycling. However, none of the angles tested were fully effective in sealing the implant-abutment interface.
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Introduction: Considering oral rehabilitation with dental implants, many studies have aimed at improving bone regeneration through the use of biomaterials. Objective: This study aimed at comparing bone neoformation in patients undergoing bilateral maxillary sinus surgery with two bovine biomaterials. Materials and Methods: This is a randomized, blinded, clinical crossover, and divided mouth study. Ten participants with an indication of maxillary sinus enlargement were selected and underwent surgical treatment with Bio-Oss® graft biomaterial (graft 1) on one side and Lumina-Porous® graft biomaterial (graft 2) on the other. The samples were collected after nine months and fixed and then decalcified in 10% ethylenediamine tetra-acetic acid (EDTA) solution for 30 days to process and make histological slides. Connective and bone tissue were further analyzed to identify the amount of newly formed bone. Results: The graft 1 group had a greater formation of vital mineralized tissue when compared to the graft 2 group (p = 0.01). For nonvital mineralized tissue and amount of connective tissue, there was no statistical difference (p = 0.21 and p = 0.09, respectively). The medullary spaces were larger in the graft 2 group. The group treated with graft 1 presented a higher percentage of osteoclasts and viable osteocytes compared to the graft 2 group (p = 0.014 and p = 0.027, respectively). Conclusion: Every day, new alternative biomaterials are offered as an option in oral rehabilitation. In this study, both treatments induced bone neoformation after 9 months; however, the group treated with Bio-Oss® showed a higher percentage of vital mineralized bone tissue.
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ABSTRACT Objective: The aim of this study was to evaluate bone microdamage in sites prepared for implant placement by using an ex vivo model with three drilling rotation speeds. Methods: Bovine bone ribs were used for the creation of 18 osteotomy sites at different rotation speeds: 1200 rpm, 800 rpm, and 400 rpm. Specimens were stained with xylenol orange and prepared for histological analysis by using fluorescence and polarized light microscopies. Bone microdamage was evaluated by number and based on total bone area, as follows: microfracture density (Fr.D = n/mm2), microcrack morphology (diffuse or linear), and density (Cr.D = n/mm2), and presence of bone chips. To complement the analysis, linear microcracks were assessed by using confocal microscopy for three-dimensional visualization. Results: Bone microdamage on the osteotomy sites included microcracks, diffuse damages, microfracture, and bone chip formation. There was an association between bone microdamage and cancellous bone (p 0.0016), as well as a positive correlation between Fr.D and Cr.D (p 0.05, r 0.54). BM occurrence was not different between the three rotation speeds. In 3D, the height of the microcrack depth was 60.81 µm. Conclusion: Bone microdamage occurs during osteotomy, and the ex vivo model used was effective for the assessment of these biomechanical parameters. In addition, microdamage was not influenced by the drilling rotation speed in this experimental condition.
RESUMO Objetivo: O objetivo desse estudo foi avaliar os microdanos ósseos em locais preparados para a instalação de implantes utilizando um modelo ex vivo acessando três velocidades de rotação de perfuração. Métodos: Fragmentos ósseos de costela bovina foram utilizados para a criação de 18 sítios de osteotomia em diferentes velocidades de rotação: 1200 rpm, 800 rpm e 400 rpm. As amostras foram coradas com Alaranjado de Xilenol e preparadas para análise microscópica em fluorescência e luz polarizada. Os microdanos ósseos foram avaliados em número e calibrados com base na área total óssea: densidade de microfraturas (Fr.D = n/mm2), morfologia (difusa ou linear) e densidade de microtrincas (Cr.D = n / mm2) e presença de espículas ósseas. Para complementar a análise, microtrincas lineares foram avaliadas por meio de microscopia confocal para visualização tridimensional. Resultados: Os microdanos ósseos incluíram microtrincas, danos difusos, microfraturas e formação de espículas. Houve uma associação entre MO e localização em osso esponjoso (p=0,0016), bem como uma correlação positiva entre Fr.D e Cr.D (p=0,05, r = 0,54). A ocorrência de microdanos ósseos não foi diferente entre as três velocidades de rotação utilizadas. Em 3D, a profundidade maior da microfissura atingiu 60,81 µm. Conclusão: Microdanos ósseos ocorrem durante a osteotomia e podem ser acessados em um modelo ex vivo na condução de experimentos em biomecânica. Sugere-se que a presença de microdanos não é influenciada pela velocidade de rotação durante a perfuração.
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ABSTRACT Objective: Evaluate the biomechanical behavior of the influence of different internal angles of conical prosthetic connections in fixed partial prostheses of three elements, through the tridimensional finite element method. Methods: Two different models of segment of the posterior portion of the mandible, with two implants with conical connections at angulations of 11.5 and 16 degrees. Afterwards, and occlusal load of 180N was used, and divided into 2 points of application on the premolar, and 400N divided into 5 points of application on the molar. Data were acquired as the tensile, compressive and shear stresses on cortical and medullary bone, and von Mises stresses on implants and prosthetic components of two implants in both in three-unit fixed partial prosthesis. In the quantitative analysis, both in cortical and medullary bone, the tension peaks in tensile, compression, and shear forces were higher for the CM16 group. Results: When analyzing qualitatively, the cortical and medullary bones presented a greater stress around the implant platform with a higher incidence in the implant in the molar region. In the von Misses analysis in both groups, the tensions were concentrated in the cervical region of the implants, in the first threads, in the premolar and molar regions. Regarding prosthetic pillars, the stress concentration was located in the region of contact with the implant. Conclusion: The increased angulation of conicity of the internal conical connections represents a determinant factor to increase in stress concentration in the implants, prosthetic components and adjacent structures, such as the cortical and medullary bone.
RESUMO Objetivo: Avaliar a influência das diferentes angulações internas de conexões protéticas cônicas em próteses parciais fixas de três elementos, em relação a distribuição de tensões no osso cortical e medular adjacente, também como nos implantes e componentes protéticos através do método dos elementos finitos. Métodos: Foram analisados de forma quantitativa e qualitativa, através do método de elementos finitos, as tensões de tração, compressão e cisalhamento no osso cortical e medular, e tensões de von Misses nos implantes e componentes protéticos de dois implantes, um com conexão cônica de 11.5 graus e o outro de 16 graus. Ambos em prótese múltipla de três elementos. Resultados: Na análise quantitativa, tanto no osso cortical quanto no medular, os picos de tensão nas forças de tração, compressão, e de cisalhamento foram maiores para o grupo CM16, se comparado ao CM11,5, exceto a força de cisalhamento do osso cortical, que obteve valores muito próximos em ambos os grupos. Ao se analisar qualitativamente, os ossos corticais e medulares apresentaram um maior stress ao redor da plataforma dos implantes com incidência maior no implante na região do molar. Na análise von Misses em ambos os grupos, as tensões concentraram-se na região cervical dos implantes, nas primeiras roscas, nas regiões de pré-molar e molar. No que diz respeito aos pilares protéticos, a concentração de tensões foi localizada na região de contato com o implante. Conclusão: Podemos concluir que conforme o ângulo da interface implante-pilar aumenta, ocorre uma incidência maior de tensões em todas as áreas envolvidas nesse estudo.
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Background. Maxillary bone atrophy with a considerable amount of pneumatization and anterior expansion of the maxillary sinus might be a situation limiting oral rehabilitation with osseointegrated implants. Therefore, the present study aimed to biomechanically evaluate two rehabilitation techniques for maxillary bone atrophy: all-on-four and long trans-sinus implants. Methods. Two three-dimensional models consisting of atrophic maxilla with four implants were simulated. In the M1 model, two axially inserted anterior implants and two tilted implants, 15 mm in length, placed tangential to the maxillary sinus's anterior wall were used. In the M2 model, two axially inserted anterior implants and two trans-sinus tilted implants, 24 mm in length, were used. For the finite element analysis (FEA), an axial load of 100 N was applied on the entire extension of the prosthesis, simulating a rehabilitation with immediate loading. The peri-implant bone and the infrastructure were analyzed according to the Mohr-Coulomb and Rankine criteria, respectively. Results. The results were similar when the stresses on peri-implant bone were compared: 0.139 and 0.149 for models 1 and 2, respectively. The tension values were lower in the model with trans-sinus implants (27.99 MPa). Conclusion. It was concluded that the two techniques exhibited similar biomechanical behavior, suggesting that the use of long trans-sinus implants could be a new option for atrophic maxilla rehabilitation.
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BACKGROUND: A retrospective cohort study was performed to evaluate the immediate effect on the oropharynx dimensions from different mandibular advancements in patients undergone counterclockwise rotation (CCW) of the maxillomandibular complex. MATERIAL AND METHODS: 138 CBCT images of patients, who had undergone orthognathic surgery, were identified from Dolphin Imaging archive according to pre- (T0) and post-operative (T1) times. Each pre-operative CBCT image was selected considering retrognathic mandible. Superimpositions of CBCT images were performed to measure mandibular advancement at B point in millimeters (mm) and divided into three groups: G1 (< 5 mm), G2 (between 5 and 10 mm) and G3 (> 10 mm). For evaluating oropharynx dimension at T0 and T1 for each group, medial sagittal area (MSA), volume, and minimum cross-sectional axial area (CSA) were measured on Dolphin Imaging. Pearson correlation verified reliability of method. Paired t-test were applied to compare values of measurements between T0 and T1 (p ≤ 0.05). RESULTS: 88 CBCT images were included. Method was reliable (r ≥ 0.93). According to MSA, volume and CSA values from G1, there was no significant difference between T0 and T1. CSA values presented significant difference comparing T0 and T1 in G2 (p ≤ 0.05). In subjects of G3, measurements increased in T1 significantly affecting oropharynx dimension. CONCLUSIONS: MSA, volume and CSA values showed a significant increase affecting upper airway in advancements higher than 10 mm. Mandibular advancement range showed different effects in the airway space and should be considered to achieve favorable post-operative results in the oropharynx dimensions. Key words:Retrognathia, orthognathic surgery, three-dimensional imaging, oropharynx, airway.
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PURPOSE: To evaluate the fracture resistance after the thermal and mechanical fatigue of feldspathic, lithium disilicate, and resin-modified CAD/CAM monolithic crowns cemented onto a universal post abutment. MATERIALS AND METHODS: A right second mandibular molar was designed in CAD/CAM software, and 30 crowns were machined using three different materials (n = 10): feldspathic ceramic, finished only with a glaze cycle (G1); lithium disilicate, sintered and finished with a glaze cycle (G2); and resin, modified by nanoceramic and finished with rubber (G3). All crowns were cemented under a constant 50 N load, the excess cement was removed, and the crowns were light-cured for 30 seconds. After being immersed in deionized water for 7 days, the crowns were submitted to thermal cycling, which consisted of varying the temperature from 2 to 50°C for 350,000 cycles, and mechanical cycling in a fatigue simulator, where a 250 N load was applied for 1,000,000 cycles at 2 Hz. The resistance of each crown was verified in a compression-to-failure test at 1 mm/min in a universal test machine. The groups were compared using one-way ANOVA with a Bonferroni post hoc test and Weibull statistics. RESULTS: The resin-modified group was the least resistant group (1755 ± 124 N), followed by the feldspathic (2147 ± 412 N) and lithium disilicate groups (2804 ± 303 N). The Weibull statistics demonstrated that lithium disilicate is the most reliable material and has the lowest fracture probability. CONCLUSIONS: It was possible to conclude that all of the tested CAD/CAM materials can be used as monolithic, implant-supported molar crowns.
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Desenho Assistido por Computador , Coroas , Materiais Dentários/química , Falha de Restauração Dentária , Resinas Acrílicas , Silicatos de Alumínio , Porcelana Dentária , Análise do Estresse Dentário , Humanos , Técnicas In Vitro , Mandíbula , Teste de Materiais , Dente Molar , Compostos de Potássio , Propriedades de SuperfícieRESUMO
Introdução: Como uma opção de tratamento ao edentulismo mandibular foi desenvolvido o conceito All-on-4®, uma técnica de ancoragem com a instalação de quatro implantes distribuídos na região anterior da mandíbula edêntula para uma reabilitação total implantossuportada. Objetivo: Neste estudo, analisamos pelo método de elementos finitos o comportamento biomecânico dos implantes e tecidos ósseos. Material e métodos: Foram utilizados 3 modelos tridimensionais computadorizados, cada um com 4 implantes hexágono externo 3,75x13mm na região interforames mentuais, os implantes anteriores mantidos na posição axial e a variação ocorreu nos implantes posteriores: grupo 1, implantes posteriores retos; grupo 2, implantes posteriores com inclinação em 17° e grupo 3, com implantes posteriores inclinados em 30°. Uma carga axial de 150N foi aplicada nos molares e de 100N nos pré-molares bilateralmente. Resultados: Após análises evidenciou-se que nos grupos 17° (13,68Mpa, 34,76Mpa e 14,36Mpa para as tensões de tração, compressão e cisalhamento respectivamente) e 30° (14,26Mpa, 23,14Mpa e 10,31Mpa para as tensões de tração, compressão e cisalhamento respectivamente) apresentaram menores picos de tensão no osso. O mesmo padrão de distribuição de tensões foi observado para os implantes, com redução quando inclinamos os implantes distais. Conclusão: Os resultados mostraram que a angulação dos implantes favoreceu a distribuição das tensões no osso e implantes, interferindo positivamente na performance biomecânica das reabilitações totais implantossuportadas em mandíbulas edêntulas, considerando que no grupo dos implantes retos os valores das tensões foram maiores.
Introduction: As a treatment option for mandibular edentulism, the All-on-4® concept was developed, an anchoring technique with the installation of four implants distributed in the anterior region of the edentulous mandible for total implant-supported rehabilitation. Objective: In this study, we analyzed by the finite element method the biomechanical behavior of implants and bone tissues. Material and methods: Three computerized three-dimensional models were used, each with 4 external hexagon 3.75x13mm implants in the mental interforam region, the anterior implants kept in the axial position and the variation occurred in the posterior implants: group 1, straight posterior implants; group 2, posterior implants inclined at 17° and group 3, posterior implants inclined at 30°. An axial load of 150 N was applied to the molars and 100 N to the premolars bilaterally. Results: After analysis, it was found that in the 17° (13.68Mpa, 34.76Mpa and 14.36Mpa groups for tensile, compressive and shear stresses respectively) and 30 ° (14.26Mpa, 23.14Mpa and 10.31Mpa for tensile, compressive and shear stresses respectively) presented lower stress peaks in the bone. The same pattern of stress distribution was observed for the implants, with reduction when the distal implants were tilted. Conclusion: The results showed that the angulation of the implants favored the distribution of stresses in the bone and implants, positively interfering in the biomechanical performance of the total implant-supported rehabilitations in edentulous jaws, considering that in the group of straight implants the stress values were higher.
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Humanos , Tecidos , Dente Pré-Molar , Osso e Ossos , Dente Molar , Reabilitação Bucal , Arcada Parcialmente Edêntula , Implantação Dentária , MandíbulaRESUMO
Aim: The effect of cavity-cleaning agents on shear bonding strength between self-etching adhesives and dentin was evaluated. Methods: Twenty-five healthy human third molars were worn to obtain flat middle dentin. The samples were randomly divided into five groups according to the cleaning agent used: group CB not treated with any cavity disinfectants and served as control. Following groups, dentin surfaces were treated with 2% chlorhexidine (CHX group); 3% hydrogen peroxide (HP group); calcium hydroxide water (CH group); and 70% ethyl ethanol (E group). The dentin surfaces were cleaned by friction for 20 s and dentine bonding agent, Clearfil SE Bond, was applied. Cylinders (5.0 mm ï´ 1.2 mm, n = 19) of fluid composite resin were placed on the dentin surface, and the teeth were stored in deionized water at 37°C for 24 h. Subsequently, the samples were subjected to the shear bonding test, and the obtained values were subjected to one-way ANOVA and Tukey's test (α = 0.05). The failure pattern was analyzed descriptively by examining the specimens with a stereoscope at a magnification of 4ï´, and failure was classified into adhesive, cohesive or mixed type. Results: Shear bonding was significantly lower in group HP (6.17 ± 5.69 MPa). The groups CB, CHX, CH and E were statiscally similar, 22.15 ± 6.54MPa; 18.40 ± 7.26MPa; 18.07 ± 5.98MPa ; 16.43 ± 6.19MPa respectively. The failure modes observed were only adhesive and mixed. Conclusion: The use of 2% chlorhexidine, calcium hydroxide water, and 70% ethyl ethanol did not negatively affect bond strength. Only 3% hydrogen peroxide is contraindicated as a cavity cleaner in adhesive restorative procedures when self-etching system is used
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Clorexidina , Colagem Dentária , Adesivos DentináriosRESUMO
OBJECTIVES: To quantitatively compare metal artefacts produced by implants in different maxillomandibular regions on cone beam CT (CBCT) images. METHODS: A total of 200 implants selected from CBCT examinations were divided into four groups: Group 1 (n = 50)-implants located in the anterior maxilla; Group 2 (n = 50)-implants located in the posterior maxilla; Group 3 (n = 50)-implants located in the anterior mandible and Group 4 (n = 50)-implants located in the posterior mandible. The implants were further classified as isolated or adjacent to other implants. Three axial reconstructions were selected for each sampled implant (apical, middle and cervical). On each slice, the artefacts produced by the implants were counted. The Mann-Whitney test was used to compare the variables between groups. The Kruskal-Wallis and Student-Newman-Keuls tests were used to compare the axial reconstructions. RESULTS: The mandible showed a greater number of artefacts than the maxilla (apical image: p = 0.0024; middle image: p < 0.0001). The anterior region produced more artefacts than the posterior region (apical image: p = 0.0105; middle image: p < 0.0316). There was no significant difference in the number of artefacts between isolated and adjacent implants, and the cervical image was most affected by artefacts. CONCLUSIONS: Dental implants always produce metal artefacts in CBCT images, and these artefacts are affected by the anatomical location in the dental arch.
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Artefatos , Tomografia Computadorizada de Feixe Cônico , Implantes Dentários , Arcada Osseodentária/diagnóstico por imagem , Estudos Transversais , Humanos , Estudos RetrospectivosRESUMO
O avanço tecnológico tem se mostrado um grande aliado em diversas áreas, assim como na odontologia. O surgimento da tecnológica CAD/CAM (Computer Aided Design/Computer Aided Manufacturing) na década de 1950 trouxe outra realidade para a prática clínica diária. Previamente todo o processo laboratorial de trabalhos protéticos era demorado e puramente físico, atualmente a fabricação das peças protéticas demanda um menor tempo devido a utilização do meio digital, o que consequentemente diminui as consultas aos Cirurgiões-Dentistas. A adição de ferramentas digitais no planejamento e na execução dos tratamentos odontológicos alterou completamente o workflow, fazendo com que a busca para um aperfeiçoamento seja constante visando sempre o melhor atendimento e qualidade dos tratamentos realizados. Dessa forma este trabalho tem o objetivo de realizar uma revisão crítica da literatura sobre a aplicabilidade clínica da tecnologia CAD-CAM em Odontologia.
The technological advance has been shown to be a greatly in several areas, as well as in dentistry. The emergence of the technological CAD / CAM (Computer Aided Design / Computer Aided Manufacturing) in the 1950s brought another reality to daily clinical practice. Previously, the entire laboratory process of prosthetic work was time consuming and purely physical, currently the manufacture of prosthetic work requires less time due to the use of the digital medium, which consequently decreases the dentist appointments. The addition of digital tools in the planning and execution of dental treatments has completely altered the workflow, making the search for a constant improvement, always aiming at the best care and quality of treatment performed. Thus, this paper has the objective of performing a critical review of the literature on the clinical applicability of CAD / CAM technology in dentistry.
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Tecnologia Odontológica , Odontologia , Computadores , Desenvolvimento Tecnológico , Desenho Assistido por Computador , Impressão TridimensionalRESUMO
PURPOSE: The classification of impacted maxillary third molars (IMTMs) facilitates interdisciplinary communication and helps estimate the degree of surgical difficulty. Thus, this study aimed to develop a 3-dimensional classification of the position and depth of impaction of IMTMs and to estimate their prevalence with respect to gender and age. MATERIALS AND METHODS: This cross-sectional retrospective study analyzed images in sagittal and coronal cone-beam computed tomography (CBCT) sections of 300 maxillary third molars. The proposed classification was based on 3 criteria: buccolingual position (buccal, lingual, or central), mesial-distal position (mesioangular, vertical, or distoangular), and depth of impaction (low, medium, or high). CBCT images of IMTMs were classified, and the associations of the classifications with gender and age were examined using analysis of variance with the Scheffé post-hoc test. To determine the associations among the 3 classifications, the chi-square test was used (P<.05). RESULTS: No significant association of the classifications with gender was observed. Age showed a significant relationship with depth of impaction (P=.0001) and mesial-distal position (P=.005). The most common positions were buccal (n=222), vertical (n=184), and low (n=124). Significant associations among the 3 tested classifications were observed. CONCLUSION: CBCT enabled the evaluation of IMTMs in a 3-dimensional format, and we developed a proposal for a new classification of the position and depth of impaction of IMTMs.
RESUMO
O objetivo deste estudo foi descrever uma técnica de tratamento conservadora, cuja conduta preconizada foi a realização da descompressão seguida pela enucleação cística através do relato de um caso de cisto periapical de grande extensão. Paciente de 50 anos de idade, melanoderma, apresentando cisto periapical com aproximadamente 4,5 cm em seu maior diâmetro associado ao incisivo central inferior esquerdo. Na primeira etapa do tratamento, foi realizada descompressão cística e biopsia incisional, cujo exame histopatológico confirmou o diagnóstico clínico. Após 25 semanas de acompanhamento, houve uma considerável regressão do tamanho da lesão e a mesma foi enucleada sem comprometimento dos elementos dentários envolvidos e dos tecidos adjacentes. O relato de caso evidenciou que o tratamento cirúrgico e conservador pode ser um recurso em cistos periapicais de maior dimensão, sendo importante a cooperação do paciente no acompanhamento pós-operatório.
The aim of this study was to describe a conservative treatment technique, the recommended therapeutic of which was performed decompression and followed by cystic enucleation through the report of a large periapical cyst case. A 50-year-old melanoderma patient presented a periapical cyst with approximately 4,5 cm in its largest diameter associated with the left lower central incisor. In the first stage of the treatment, cystic decompression and incisional biopsy were performed; whose histopathological examination confirmed the clinical diagnosis. After follow-up, there was a considerable regression of the size of the lesion and it could be enucleated without compromising the dental elements involved and adjacent tissues. The case report showed that surgical and conservative treatment may be a resource in larger periapical cysts, and patient cooperation in postoperative follow-up is very important.
Assuntos
Cirurgia Bucal , Cisto Radicular , Ferimentos e Lesões , Cooperação do Paciente , Descompressão Cirúrgica , Descompressão , Recursos em SaúdeRESUMO
OBJECTIVE: To evaluate the influence of lip retraction on cone beam computed tomography (CBCT) assessment of bone and gingival tissues on the labial surface of the anterior maxilla. STUDY DESIGN: A retrospective study was conducted using measurements of bone and gingival tissues collected from 120 maxillary incisors. The thicknesses of the bone and gingival tissues of different regions were measured on CBCT images, with and without a lip retractor. The thicknesses of the gingival tissues obtained from CBCT were correlated with measurements performed by clinical probing. RESULTS: The thickness of bone in the more cervical region presented a higher mean value for exams performed with a lip retractor (P = .021). The thickness of bone found a significant correlation with the thickness of the gingiva (P ≤ .020) with a lip retractor in CBCT exams. The thickness of the gingival tissue obtained from CBCT scans with lip retraction found significant correlations with those obtained clinically (P ≤ .001). CONCLUSIONS: The use of lip retractors is a simple and reliable practice that allows the measurement of gingival tissues on CBCT images. This practice can exempt a patient from an invasive clinical procedure for measuring the thickness of the gingival tissue for implant cases of the anterior segment.
Assuntos
Tomografia Computadorizada de Feixe Cônico , Gengiva/diagnóstico por imagem , Incisivo/diagnóstico por imagem , Lábio/anatomia & histologia , Maxila/diagnóstico por imagem , Estudos Transversais , Equipamentos e Provisões , Feminino , Humanos , Masculino , Estudos RetrospectivosRESUMO
The purpose of this study was to evaluate the effects of steam autoclave sterilization on the tensile strength of two types of resin cements used to bond customized CAD/CAM zirconia abutments onto titanium bases. Forty sets of zirconia abutments cemented to screwed titanium bases of implants analogs were divided into 4 groups (n = 10). Two groups were treated with a conventional chemically activated resin cement (ML, Multilink Ivoclar Vivadent) and the other two groups with a self-adhesive dual resin cement (RelyX U200, 3M ESPE). One group from each cement was submitted to steam autoclaving. The autoclave sterilization cycle was performed after 72 hours of cementation for 15 minutes at 121°C and 2.1 Kgf/cm2. The samples were subjected to tensile strength testing in a universal testing machine (200 Kgf, 0.5 mm/min), from which the means and standard deviations were obtained in Newtons. Results showed (via ANOVA and Tukey's test; α = 0.05) that in the absence of steam autoclaving, no difference was observed in tensile strength between the cements tested: ML: 344.87 (93.79) and U200: 280 (92.42) (P = .314). Steam autoclaving, however, significantly increased tensile strength for the ML: 465.42 (87.87) compared to U200: 289.10 (49.02) (P < .001). Despite the significant increase in the ML samples (P = .013), autoclaving did not affect the tensile strength of the U200 samples (P > 0.05). The authors concluded that steam autoclaving increases the mean tensile strength of the chemically activated cement compared to the dual-cure self-adhesive cement. The performance of both cements evaluated was similar if the sterilization step was disconsidered.
Assuntos
Colagem Dentária , Cimentos de Resina , Análise do Estresse Dentário , Teste de Materiais , Vapor , Resistência à Tração , ZircônioRESUMO
Introduction: When stress and strain levels in the bone-implant system exceed It's capacity, a mechanical fatigue occurs, resulting in collapse and loss of osseointegration. Objective: Analyze biomechanical behavior in single implant-supported prosthesis with implants of different diameters in the posterior mandible. Material and method: Three different finite element models of Cone-Morse implants with the same height were created, varying the diameter (3.3 mm, 4.1 mm and 4.8 mm). The mandibular first molar area was the location of the implant, with It´s component and overlying prosthetic crown. The jawbone was composed of cortical and cancellous bone. Refined mesh of 0.5 mm was created in the critical interfaces to be analyzed. The loading of the models was performed at the point of occlusal contact with an occlusal load of 400 N. Result: Maximum stress and strain occurred in the cervical regions of the implants in all groups, either in the implants or in components as well as in the analysis of cortical bone. The greater the diameter, the lower the stress and strain found in the implant. The 3.3 mm group had the highest strain in peri-implant cortical bone, and the 4.1 mm group had the smallest deformation, significantly lower than in the 4.8 mm group. Conclusion: Although the biggest implant diameter (4.8 mm) appears to have lower values of stress and strain, the group of intermediate implant diameter (4.1 mm) showed less deformation rate in the cortical peri-implant bone. Therefore it is concluded that the 4.1 mm implant platform presented a more biomechanically effective peri-implant bone maintenance.
Introdução: Quando os níveis de tensão e compressão gerados no sistema osso-implante excederem a capacidade óssea ocorre uma fadiga mecânica, resultando em colapso e perda da osseointegração. Objetivo: Analisar o comportamento biomecânico em próteses unitárias implanto-suportadas com implantes de diferentes diâmetros na região posterior de mandíbula. Material e método: Foram criados três modelos de elementos finitos de implantes cone-Morse de mesmo comprimento, variando-se o diâmetro: 3,3 mm, 4,1 mm e 4,8 mm. A localização do implante foi a região de primeiro molar inferior, com componente e coroa protética sobrejacentes. A mandíbula foi composta por osso cortical e medular. Foi criada malha refinada de 0,5 mm nas interfaces criticas a serem analisadas. O carregamento dos modelos foi realizado nos pontos de contatos oclusais, com uma carga oclusal de 400 N. Resultado: Tensão e deformação máximas ocorreram nas regiões cervicais dos implantes em todos os grupos, tanto na análise dos implantes e componentes quanto na análise do osso cortical. Quanto maior foi o diâmetro, menores foram tensão e deformação encontradas no implante. O grupo 3,3 mm apresentou a maior deformação em osso cortical periimplantar, tendo o grupo 4,1 mm a menor deformação, significantemente menor em relação ao grupo 4,8 mm. Conclusão: Apesar de o implante de maior diâmetro (4,8 mm) ter apresentado os menores valores de tensão e deformação, o grupo do implante de diâmetro intermediário (4,1 mm) mostrou menor taxa de deformação em osso cortical periimplantar. Portanto conclui-se que o implante de plataforma 4,1 mm apresentou-se mais efetivo biomecanicamente para manutenção óssea periimplantar.