Effect of electrochemically dealloying Ti6Al4V abutments on human gingival fibroblasts / 口腔疾病防治

Objective@#To investigate the effects of electrochemically dealloying of Ti6Al4V abutments on human gingival fibroblasts (HGFs) and to provide experimental evidence for surface modification of implant abutments.@*Methods@#The samples were divided into an NC group (negative control, no other treatment on a smooth surface), an NM-1 group (nanomesh-1, electrochemical dealloying treatment in 1 mol/L NaOH 1 h on 2 V voltage), and an NM-2 group (nanomesh-2, electrochemical dealloying treatment in 5 mol/L NaOH 1 h on 2 V voltage). The surface morphologies of the samples and the adhesion of HGFs on the sample surfaces were observed with scanning electron microscopy (SEM). The surface hydrophilicities of the samples were measured with a contact angle measuring instrument. The proliferation of HGFs on the different samples were evaluated with CCK-8, and the expression of adhesion-related genes, including collagen Ⅰ (COL1A1), collagen Ⅲ (COL3A1), fibronectin 1 (FN1), focal adhesion kinase (FAK), vinculin (VCL), integrin α2 (ITGA2), and integrin β1 (ITGB1), on the different samples was measured with qRT-PCR. The expression of vinculin on the surfaces of HGFs was observed via confocal laser scanning microscopy (CLSM) after immunofluorescent staining. Collagen fiber secretion and syntheses of HGFs from different samples were evaluated via Sirius red staining.@*Results@#SEM revealed the formation of ordered and uniform three-dimensional mesh structures on the surfaces of the NM-1 and NM-2 groups, with grid diameters of approximately 30 nm for the NM-1 group and approximately 150 nm for the NM-2 group. Compared with that of the NC group, the water contact angles of the NM-1 group and NM-2 groups were significantly lower (P<0.000 1). Cell proliferation in the NM-1 group was significantly greater than that in the NC group (P<0.01). Moreover, there was no significant difference in the water contact angles or cell proliferation between the NM-1 group and the NM-2 group. SEM revealed that HGFs were adhered well to the surfaces of all samples, while the HGFs in the NM-1 and NM-2 groups showed more extended areas, longer morphologies, and more developed pseudopodia than did those in the NC group after 24 h. qRT-PCR revealed that the expression levels of the adhesion-related genes COL1A1, COL3A1, FN1, FAK and VCL in the NM-1 group were significantly greater than those in the NC and NM-2 groups (P<0.01). The expression of vinculin protein in the NM-1 group was the highest, and the number of focal adhesions was greatest in the NM-1 group (P<0.01). The results of Sirius red staining showed that the NM-1 group had the highest secretion and syntheses of collagen fibers (P<0.000 1).@*Conclusion@#The three-dimensional nanomechanical structure of Ti6Al4V modified by electrochemical dealloying promoted the adhesion, proliferation, collagen fiber secretion and syntheses of HGFs, and electrochemical dealloying of Ti6Al4V with a grid diameter of approximately 30 nm obviously promoted HGF formation.

Complexos polieletrólitos de quitosana e xantana carregados com ativos naturais e sintéticos: estudo físico/químico e microbiológico para aplicação de drug delivery / Polyelectrolyte complexes of chitosan and xanthan loaded with natural and synthetic actives: physicochemical and microbiological study for drug delivery application

A eficácia dos implantes osseointegrados é amplamente reconhecida na literatura científica. Contudo, infiltrações bacterianas na junção implante-pilar podem desencadear inflamação nos tecidos circundantes, contribuindo para a evolução de condições mais sérias, como a peri-implantite. O objetivo desse estudo foi produzir complexos polieletrólitos (PECs) de quitosana (Q) e xantana (X) em forma de membranas, carregá-las com ativos naturais e sintéticos antimicrobianos, caracterizálas estruturalmente e avaliá-las frente a degradação enzimática, cinética de liberação e ações antimicrobianas com finalidade de aplicação para drug delivery. Membranas de QX a 1% (m/v) foram produzidas em três proporções, totalizando doze grupos experimentais: QX (1:1); QX (1:2), QX (2:1), QX-P (com própolis) (1:1); QX-P (1:2); QX-P (2:1); QX-C (com canela) (1:1); QX-C (1:2); QX-C (2:1) e CLX (com clorexidina 0,2%) (1:1); CLX (1:2); CLX (2:1). Para os estudos de caracterização foram feitas análises da espessura em estado seco; análises morfológicas superficial e transversal em Microscopia Eletrônica de Varredura (MEV); análise estrutural de espectroscopia de infravermelho por transformada de Fourier (FTIR); análise de degradação por perda de massa sob ação da enzima lisozima; e análise da cinética de liberação dos ativos em saliva artificial. Para os testes microbiológicos, análises de verificação de halo de inibição e ação antibiofilme foram feitas contra cepas de Staphylococcus aureus (S. aureus) e Escherichia coli (E. coli). Os resultados demonstraram que a espessura das membranas variou conforme a proporção, sendo que o grupo QX (1:2) apresentou a maior média de 1,022 mm ± 0,2, seguida respectivamente do QX (1:1) com 0,641 mm ± 0,1 e QX (2:1) com 0,249 mm ± 0,1. Nas imagens de MEV é possível observar uma maior presença de fibras, rugosidade e porosidade nos grupos QX (1:2) e QX (1:1) respectivamente, e, no QX (2:1) uma superfície mais lisa, uniforme e fina. No FTIR foram confirmados os picos característicos dos materiais isoladamente, além de observar as ligações iônicas que ocorreram para formação dos PECs. Na análise de degradação, os grupos com ativos naturais adicionados tiveram melhores taxas de sobrevida do que os grupos QX. No teste de liberação, os grupos QX-P tiveram uma cinética mais lenta que os QX-C, cuja liberação acumulada de 100% foi feita em 24 h. Já nos testes do halo inibitório, somente os grupos CLX tiveram ação sobre as duas cepas, e os QX-P tiveram sobre S. aureus. Nas análises antibiofilme, os grupos CLX apresentaram as maiores taxas de redução metabólica nas duas cepas (± 79%); os grupos QX-P apresentaram taxas de redução similares em ambas as cepas, porém com percentual um pouco maior para E. coli (60- 80%) e os grupos QX-C tiveram grande discrepância entre as duas cepas: de 35 a 70% para S. aureus e 14 a 19% para E. coli. Pode-se concluir que, frente as análises feitas, o comportamento do material foi afetado diretamente pelos ativos adicionados a matriz polimérica. As proporções de Q ou X afetaram somente a espessura final. Quanto a aplicação proposta de drug delivery, os dispositivos apresentaram grande potencial, principalmente os grupos CLX e QX-P. (AU)

The effectiveness of osseointegrated implants is widely recognized in scientific literature. However, bacterial infiltrations at the implant-abutment interface may trigger inflammation in surrounding tissues, contributing to the development of more serious conditions, such as peri-implantitis. The aim of this study was to produce chitosan (Q) and xanthan (X) polyelectrolyte complexes (PECs) in the form of membranes, load and evaluate them for enzymatic degradation, release kinetics, and antimicrobial actions for drug delivery applications. QX membranes at 1% (w/v) were produced in three proportions, totaling twelve experimental groups: QX (1:1), QX (1:2), QX (2:1), QX-P (with propolis) (1:1), QX-P (1:2), QX-P (2:1), QX-C (with cinnamon) (1:1), QX-C (1:2), QX-C (2:1), and CLX (with 0.2% chlorhexidine) (1:1), CLX (1:2), CLX (2:1). Characterization studies included analyses of dry state thickness, surface and crosssectional morphology using Scanning Electron Microscopy (SEM), structural analysis by Fourier Transform Infrared (FTIR) spectroscopy, mass loss degradation analysis under lysozyme action, and active release kinetics analysis in artificial saliva. Microbiological tests included verification analyses of inhibition halos and antibiofilm action against strains of Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli). Results showed that membrane thickness varied according to proportion, with group QX (1:2) presenting the highest average of 1.022 mm ± 0.2, followed by QX (1:1) with 0.641 mm ± 0.1, and QX (2:1) with 0.249 mm ± 0.1. SEM images showed greater presence of fibers, roughness, and porosity in groups QX (1:2) and QX (1:1) respectively, while QX (2:1) exhibited a smoother, more uniform, and thinner surface. FTIR confirmed characteristic peaks of the materials individually, besides showing ionic bonds formed for PECs. Degradation analysis revealed that groups with added natural actives had better survival rates than QX groups. In release tests, QX-P groups exhibited slower kinetics than QX-C, with 100% cumulative release achieved in 24 h. inhibitory halo tests, only CLX groups exhibited action against both strains, while QX-P acted against S. aureus. Antibiofilm analyses showed CLX groups with the highest metabolic reduction rates in both strains (± 79%); QX-P groups showed similar reduction rates in both strains, slightly higher for E. coli (60-80%), and QX-C groups had a significant discrepancy between strains: 35-70% for S. aureus and 14-19% for E. coli. In conclusion, material behavior was directly affected by added actives to the polymeric matrix. Proportions of Q or X only affected final thickness. Regarding proposed drug delivery applications, the devices showed great potential, especially CLX and QX-P groups.(AU)

The assessment of periimplant soft tissue condition with morse taper abutment connection: a rapid review

Aim: This study aims to evaluate the clinical assessment results of periimplant soft tissue with morse taper (internal abutment connection). Methods: The study was conducted using a rapid review by searching the articles from PubMed NCBI and Cochrane by using keywords. All articles were selected by the year, duplication, title, abstract, full-text, and finally, all selected articles were processed for final review. Following clinical parameters were included; Periimplant Probing Pocket Depth (PPD), Plaque Score (PS), modified Plaque Index (mPI), Mucosal Thickness (MTh), Gingival Height (GH), periimplant mucosal zenith, Pink Esthetic Score (PES), Bleeding On Probing (BOP), Sulcus Bleeding Index (SBI), and modified Gingival Index (mGI). Results: 9 selected articles were obtained from the initial literature searching count of 70 articles. The overall samples included 326 morse taper implants. Based on the evaluation, 3 out of 4 articles reported pocket depth < 4 mm, no bleeding was reported in 2 out of 4 articles. 4 out of 4 articles reported low plaque accumulation, low soft tissue recession was reported in 3 out of 3 articles, and 4 out of 4 articles reported acceptable PES values. Conclusion: The evaluations indicate that the morse taper (internal abutment connection) has favorable assessment results based on various clinical parameters

Evaluation of tensile strength after insertions andremovals of abutments on frictional Morse taper implants

ABSTRACT: This study aimed to evaluate possible changes in final retention after nine sequences of insertion and removal (SIR) of a frictional Morse taper implant/abutment system, evaluating the force required for dissociating this set between sequences, and verifying possible deformations in the implant heads. Ten implants, 13 mm long and 3.3 mm in diameter, were coupled to a universal mechanical testing machine. Ten anti-rotational abutments, 13 mm long and 3.5 mm in diameter, were connected to the implants parallel to the long axis, using an instrument called beat-connection, and subjected to tensile tests and SEM analysis. The results were analyzed using the Kruskal-Wallis test with Dunn's post-test, and the significance level was set at 5 %. There was no statistically significant difference in final retention among the nine SIRs evaluated. The force needed to uncouple the abutment from the implant increased as SIRs were performed on all ten implants, and an increase of 29.03 % was observed in the ninth SIR compared to the first SIR. After SEM analysis, no significant deformations, fractures, or cracks were observed in the implant heads.

RESUMEN: Este estudio tuvo como objetivo evaluar los posibles cambios en la retención final después de nueve secuencias de inserción y extracción (SIR) de un sistema de implante / pilar de cono de fricción Morse, evaluando la fuerza necesaria para disociar este conjunto entre secuencias y verificando posibles deformaciones en las cabezas de los implantes. Se acoplaron diez implantes, de 13 mm de largo y 3,3 mm de diámetro, a una máquina universal de ensayos mecánicos. Se conectaron a los implantes en paralelo al eje largo diez pilares antirrotacionales, de 13 mm de largo y 3,5 mm de diámetro, mediante un instrumento llamado beat-connection, y se sometieron a pruebas de tracción y análisis SEM. Los resultados se analizaron mediante la prueba de Kruskal-Wallis con la prueba posterior de Dunn, y el nivel de significancia se estableció en 5 %. No hubo diferencias estadísticamente significativas en la retención final entre los nueve SIR evaluados. La fuerza necesaria para desacoplar el pilar del implante aumentó a medida que se realizaban SIR en los diez implantes, y se observó un aumento del 29,03 % en el noveno SIR en comparación con el primer SIR. Después del análisis SEM, no se observaron deformaciones, fracturas o grietas significativas en las cabezas de los implantes.

Retention of cemented zirconia copings on TiBase abutments / Retenção de copings de zirconia cimentados sobre pilares tibase

ABSTRACT This study evaluated the influence of resin cements and glass ionomers on tensile strength and types of failure of zirconia copings cemented on titanium base abutments. Forty-two samples were prepared, which were formed by a Cone Morse implant, a titanium abutment with the fixing screw, and a zirconia structure made using a CAD/CAM system. The samples (n = 42) were randomly distributed according to the cementing agent: resin-modified glass ionomer cement (RelyX Luting 2), self-adhesive resin cement (RelyX U200), and self-curing resin cement (Multilink N). After cementation of the copings, half of the samples from each group (n = 7) were randomly selected and subjected to thermocycling (5000 cycles). A tensile load test was performed on a universal testing machine until failure occurred (1 mm). In addition, the type of failure was analyzed using the two-way analysis of variance test and Tukey's post-hoc test (α = 0.05). Lower tensile load was observed for the glass ionomer cement (p < 0.001) regardless of the evaluation period. After thermocycling, a significant reduction in tensile load values was verified for both evaluated cements (p = 0.047). For the resin cements, failures were predominantly of the screw fracture type (82.1%) already with the use of glass ionomer cement, and 28.5% of the failures were of an adhesive type between the zirconia coping and the cement. Resin cements have better stability under tensile load compared to resin glass ionomers when cementing zirconia copings on titanium base abutments.

RESUMO Este estudo avaliou influência dos cimentos resinosos e a base de ionômero de vidro na resistência à tração e os tipos de falhas de copings de zircônia cimentados sobre pilares TiBase. Foram confeccionadas 42 amostras, sendo estas formadas por implante cone morse, pilar de titânio (TiBase) com o parafuso de fixação e uma estrutura de zircônia (coping de Zr) confeccionado através do sistema CAD/CAM. As amostras (n =42) foram aleatoriamente distribuídas de acordo com o agente de cimentação: (cimento de ionômero de vidro modificado por resina [RelyXTMLuting2]; cimento resinoso autoadesivo [RelyXTM U200] e cimento resinoso autopolimerizavel (Multilink® N). Após cimentação dos copings, metade das amostras de cada grupo (n = 7) foram aleatoriamente selecionadas e submetidas a termociclagem (5000 ciclos). O Teste de resistência a tração foi realizado em uma máquina de ensaio universal, até que ocorresse a falha (1 mm/min). Adicionalmente, o tipo de falha foi analizado. Os dados foram analisados pelo teste ANOVA two-way e post teste de Tukey's (α = 0.05). Menor média de resistência a tração foi observada para o cimento de ionômero de vidro (p < 0,001) independente do período de avaliação. Após a termociclagem, foi verificada uma redução significativa nos valores de resistênca a tração, para os cimentos avaliados (p=0,047). Para os cimentos resinosos, as falhas foram predominantemente do tipo fratura do parafuso (82,1%) já com o uso do cimento de ionômero de vidro, 28,5% das falhas foram de tipo adesiva entre o coping de Zr e o cimento. Cimentos resinosos apresentam melhor estabilidade na resistência a tração em comparação a ionmeros de vidro resinosos na cimentação de copings de zircônia sobre pilares TiBase.

Comparison of residual cement between CAD/CAM customized abutments and stock abutments via digital measurement in vitro / 北京大学学报(医学版)

OBJECTIVE@#To compare the residual cement between computer aided design/computer aided manufacturing customized abutments (CCA) and stock abutments (SA), and to evaluate the feasibility of digital measurement for residual cement volume by three-dimensional scanning.@*METHODS@#Twenty master models needed in this study were all taken from one 47-year-old patient with arrested periodontitis, who had already had an implant placed at his right upper central incisor site in the Department of Periodonto-logy, Peking University School and Hospital of Stomatology. After 4 weeks of soft tissue conditioning by means of customized healing abutment, the height of peri-implant soft tissue was measured, from the implant platform to mucosal margin, as 5 mm. Using customized impression coping, the impression was taken and twenty models were fabricated and allocated to 4 groups according to the type of abutments: CCA1 (5 mm transmucosal height CCA, with margin at tissue level), CCA2 (4 mm transmucosal height CCA, with 1 mm submucosal margin), SA1 (3 mm transmucosal height SA, with 2 mm submucosal margin) and SA2 (1 mm transmucosal height SA, with 4 mm submucosal margin). Crowns were cemented to the abutments, which were seated on the working models. Excess cement was removed by a prosthodontic specialist. Thereafter, the volume of residual cement was evaluated by using three-dimensional scanning technique. The area proportion of residual cement was calculated on photographs taken by a single lens reflex camera. The weight of residual cement was weighed by an analytical balance. And the correlation of residual cement volume data with residual cement area proportion or weight of residual cement acquired by traditional methods was analyzed.@*RESULTS@#Residual cement was observed on all the experiment samples. The residual cement volume of CCA was significantly less than that of SA [(0.635 3±0.535 4) mm3 vs. (2.293 8±0.943 8) mm3, P < 0.001]. Consistently, CCA had less residual cement area proportion and weight than those of SA [area proportion: 7.57%±2.99% vs. 22.68%±10.06%, P < 0.001; weight: (0.001 5±0.001 0) g vs. (0.003 7±0.001 4) g, P < 0.001]. The residual cement volume was strongly correlated with the residual cement area proportion and residual cement weight (r>0.75, P < 0.001).@*CONCLUSION@#These in vitro results suggest that CCA minimized the residual cement more effectively than SA. The method to digitally evaluate the residual cement volume is feasible, but its validity and reliability need to be further studied.

Influence of metal bar lever-arm on screws detorque for dental prosthesis implant supported / Influência do cantilever no destorque de parafusos de barras metálicas utilizadas em próteses do tipo protocolo de Brannemark

Introduction: The cantilever length of implant-supported fixed prosthesis metal structure has been considered an important factor to transfer occlusion forces to the dental implant. Objective: This study evaluated the influence of different extensions of cantilevers of Branemark protocol implant prosthesis when submitted to mechanical thermocycling by screw loosening evaluation. Material and method: The groups G10 (n = 5), G15 (n = 5) and G20 (n = 5) were formed according to the distance in millimeters between the force application site in the cantilever and the center of the last implant. All metal structures (n = 15) were submitted to a 120 N cyclic vertical load in a chewing simulation machine (MSM-Elquip, São Carlos-SP, Brazil) under controlled temperature and moisture conditions. Two hundred and fifty thousand mechanical cycles were performed with a frequency of 2 Hz that simulates a masticatory activity similar to 3 months. To compare the data obtained regarding the loosening of the metal structure screws, implant position and sites of load application, the analysis of variance with two factors and the Tukey test were performed. Result: Statistical analysis showed that the G10 group presented greater torque loss, statistically different from G15 (p = 0.001) and G20 (p = 0.002), and there was no significant difference between groups G15 and G20. Conclusion: It can be concluded from the results that all the screws presented torque loss after simulation of 3 month masticatory activity, suggesting the need for periodical evaluation to prevent failures in the treatment.

Introdução: O comprimento do cantilever da infraestrutura de prótese implanto-suportada tem sido considerado um importante fator de transferência de força de oclusão para o implante dentário. Objetivo: Esse trabalho avaliou a influência das diferentes extensões do cantilever da prótese sobre implantes tipo protocolo de Branemark submetidas à termociclagem mecânica pela avaliação dos afrouxamentos dos parafusos de fixação. Material e método: Os grupos G10 (n=5), G15 (n=5) e G20 (n=5) foram formados de acordo com a distância, em milímetros, entre o local de aplicação de força no cantilever e o centro do último implante. Todas as barras (n=15) foram submetidas a carga vertical cíclica de 120 N em uma máquina de simulação de mastigação (MSM-Elquip, São Carlos/SP, Brasil), em condições de temperatura e umidade controladas. Foram realizados 250 mil ciclos mecânicos com frequência de 2 Hz que simulou uma atividade mastigatória correspondente a 3 meses. Para comparar os dados obtidos quanto à soltura dos parafusos da barra, a posição dos implantes e os locais de aplicação de carga, foi realizada a análise de variância com dois fatores e o teste de Tukey. Resultado: A análise estatística mostrou que o grupo G10 apresentou maior perda de torque, diferente estatisticamente de G15 (p=0,001) e G20 (p=0,002) e que não houve diferença significante entre os grupos G15 e G20. Conclusão: Pode-se concluir que todos os parafusos apresentaram perda de torque após o ensaio simulando uma atividade mastigatória de 3 meses, sugerindo a necessidade de avaliação clínica periódica afim de prevenir fracasso no tratamento.

Sealing capability and marginal fit of titanium versus zirconia abutments with different connection designs

PURPOSE: Limited data is available regarding the differences for possible microleakage problems and fitting accuracy of zirconia versus titanium abutments with various connection designs. The purpose of this in vitro study was to investigate the effect of connection design and abutment material on the sealing capability and fitting accuracy of abutments. MATERIALS AND METHODS: A total of 42 abutments with different connection designs [internal conical (IC), internal tri-channel (IT), and external hexagonal (EH)] and abutment materials [titanium (Ti) and zirconia (Zr)] were evaluated. The inner parts of implants were inoculated with 0.7 µL of polymicrobial culture (P. gingivalis, T. forsythia, T. denticola and F. nucleatum) and connected with their respective abutments under sterile conditions. The penetration of bacteria into the surrounding media was assessed by the visual evaluation of turbidity at each time point and the number of colony forming units (CFUs) was counted. The marginal gap at the implant- abutment interface (IAI) was measured by scanning electron microscope. The data sets were statistically analyzed using Kruskal-Wallis followed by Mann-Whitney U tests with the Bonferroni-Holm correction (α=.05). RESULTS: Statistically significant difference was found among the groups based on the results of leaked colonies (P<.05). The EH-Ti group characterized by an external hexagonal connection were less resistant to bacterial leakage than the groups EH-Zr, IT-Zr, IT-Ti, IC-Zr, and IC-Ti (P<.05). The marginal misfit (in µm) of the groups were in the range of 2.7–4.0 (IC-Zr), 1.8–5.3 (IC-Ti), 6.5–17.1 (IT-Zr), 5.4–12.0 (IT-Ti), 16.8–22.7 (EH-Zr), and 10.3–15.4 (EH-Ti). CONCLUSION: The sealing capability and marginal fit of abutments were affected by the type of abutment material and connection design.

Repairment of abutment and abutment screw fracture in implant prosthesis: A case report / 대한치과보철학회지

Dental implants are an effective and predictable treatment for restoration of missing teeth. However, as the use of implants increases, complications are also increasing. The mechanical complications are not only highly frequent, but also increasing as life span of an implant increases, thus, solutions should be prepared. In this report, we will present a case dealing with abutment fracture and abutment screw fracture which are the most common mechanical complication of the implant, focusing on preserving and reusing existing components by reconstructing only the damaged parts.

Long-term Retrospective Clinical Study Comparing Submerged Type with External Hex Connection and Non-submerged Type with Internal Morse Taper Connection Implants

PURPOSE: This study was aimed to compare the survival and success rates, and long-term crestal bone loss according to the use of 2 connection types of dental implants (submerged-USII and non-submerged-SSII; Osstem Implant®) by analyzing the change in alveolar bone height after 1 year under load and during final follow-up period. MATERIALS AND METHODS: Between December 2004 and August 2008, patients with two types of Osstem implants (USII and SSII) were retrieved retrospectively. A total of 92 patients with 284 implants (USII=60, SSII=224) was finally selected. Their mean follow-up period was 7.5 years. The mesial and distal alveolar crestal bone changes were measured using radiographic images and the average was calculated at 1 year after loading and during final follow-up period. RESULT: Among the 284 implants, 4 USII and 7 SSII implants were removed, indicating 93.3% and 96.9% survival rates. Of the survived implants, mean crestal bone loss 1 year after loading was 0.39 mm for USII and 0.19 mm for SSII (P=0.018). During the final follow-up, mean crestal bone loss was 0.63 mm and 0.35 mm for USII and SSII, respectively, without statistical significance (P=0.092). According to the criteria for the success and failure of the implant by Albreksson and colleagues, final success rate was estimated as 86.7% for USII and 91.5% for SSII, respectively. CONCLUSION: At 1 year after loading, the average crestal bone loss was significantly different between USII and SSII; however, both types met the criteria for implant success. During the final follow-up, both groups showed insignificant bone resorption patterns and did not show any pathological clinical symptoms. Therefore, both implants exhibited high long-term stability.

Effect of initial placement level and wall thickness on maintenance of the marginal bone level in implants with a conical implant-abutment interface: a 5-year retrospective study

PURPOSE: Implant wall thickness and the height of the implant-abutment interface are known as factors that affect the distribution of stress on the marginal bone around the implant. The goal of this study was to evaluate the long-term effects of supracrestal implant placement and implant wall thickness on maintenance of the marginal bone level. METHODS: In this retrospective study, 101 patients with a single implant were divided into the following 4 groups according to the thickness of the implant wall and the initial implant placement level immediately after surgery: 0.75 mm wall thickness, epicrestal position; 0.95 mm wall thickness, epicrestal position; 0.75 mm wall thickness, supracrestal position; 0.95 mm wall thickness, supracrestal position. The marginal bone level change was assessed 1 day after implant placement, immediately after functional loading, and 1 to 5 years after prosthesis delivery. To compare the marginal bone level change, repeated-measures analysis of variance was used to evaluate the statistical significance of differences within groups and between groups over time. Pearson correlation coefficients were also calculated to analyze the correlation between implant placement level and bone loss. RESULTS: Statistically significant differences in bone loss among the 4 groups (P<0.01) and within each group over time (P<0.01) were observed. There was no significant difference between the groups with a wall thickness of 0.75 mm and 0.95 mm. In a multiple comparison, the groups with a supracrestal placement level showed greater bone loss than the epicrestal placement groups. In addition, a significant correlation between implant placement level and marginal bone loss was observed. CONCLUSIONS: The degree of bone resorption was significantly higher for implants with a supracrestal placement compared to those with an epicrestal placement.

Influence of implant-abutment connection structure on peri-implant bone level in a second molar: A 1-year randomized controlled trial

PURPOSE: This study aimed to evaluate the effect of two different implant-abutment connection structures with identical implant design on peri-implant bone level. MATERIALS AND METHODS: This clinical study was a patient-blind randomized controlled trial following the CONSORT 2010 checklists. This trial was conducted in 24 patients recruited between March 2013 and July 2015. Implants with internal friction connection were compared to those with external hex connection. One implant for each patient was installed, replacing the second molar. Implant-supported crowns were delivered at four months after implant insertion. Standardized periapical radiographs were taken at prosthesis delivery (baseline), and one year after delivery. On the radiographs, distance from implant shoulder to first bone-to-implant contact (DIB) and peri-implant area were measured, which were the primary and secondary outcome, respectively. RESULTS: Eleven external and eleven internal implants were analyzed. Mean changes of DIB from baseline to 1-year postloading were 0.59 (0.95) mm for the external and 0.01 (0.68) mm for the internal connection. Although no significant differences were found between the two groups, medium effect size was found in DIB between the connections (Cohen's d = 0.67). CONCLUSION: Considering the effect size in DIB, this study suggested the possibility of the internal friction connection structure for more effective preservation of marginal bone.

Does the implant-abutment interface interfere on marginal bone loss? A systematic review and meta-analysis

Abstract The objective of this systematic review was to compare the conical internal connection (IC) with the external hexagonal connection (EH) on the occurrence of marginal bone loss (ΔMBL). Different databases were used to carry out the selection of the elected studies. The studies were judged according to the risk of bias as "high", "low" and "unclear" risk. For the meta-analysis we included only studies that could extract the data of ΔMBL, survival rate (SR) and probing depth (PD). No statistically significant differences were found for ΔMBL data at one, three- and five-year survival rates between implant connections (p <0.05), however statistically significant differences were found for PD between EH and IC implants (1-year follow-up) -0.53 [95%CI -0.82 to -0.24, p = 0.0004]. This present systematic review demonstrated that there are no significant differences between IC and EH implants for both ΔMBL and SR at 1, 3 e 5 years after functional loading, although better PD values were observed for implants pertaining to the IC connections. Considering the high heterogeneity, more well-delineated, randomized clinical trials should be conducted.

Implant-based factor as possible risk for peri-implantitis

Abstract Peri-implantitis is currently a topic of major interest in implantology. Considered one of the main reasons of late implant failure, there is an emerged concern whether implant characteristics could trigger inflammatory lesion and loss of supporting bone. The purpose of this narrative review is to provide an evidence based overview on the influence of implant-based factors in the occurrence of peri-implantitis. A literature review was conducted addressing the following topics: implant surface topography; implant location; occlusal overload; time in function; prosthesis-associated factors (rehabilitation extension, excess of cement and implant-abutment connection); and metal particle release. Although existing data suggests that some implant-based factors may increase the risk of peri-implantitis, the evidence is still limited to consider them a true risk factor for peri-implantitis. In conclusion, further evidences are required to a better understanding of the influence of implant-based factors in the occurrence of peri-implantitis. Large population-based studies including concomitant analyses of implant- and patient-based factors are required to provide strong evidence of a possible association with peri-implantitis in a higher probability. The identification of these factors is essential for the establishment of strategies to prevent peri-implantitis.

Influence of cantilever position and implant connection in a zirconia custom implant-supported fixed partial prosthesis: in silico analysis / Influência da posição do cantilever e da conexão do implante em um modelo de zirconia de uma prótese parcial fixa implanto-suportada: análise in sílico

Introduction: A better tension distribution on implants and abutments in implant-supported fixed partial prosthesis is essential in the rehabilitation of posterior mandible area. Objective: To evaluate the influence of cantilever position and implant connection in a zircônia custom implant-supported fixed partial prosthesis using the 3-D finite element method. Material and method: Four models were made based on tomographic slices of the posterior mandible with a zirconia custom three-fixed screw-retained partial prosthesis. The investigated factors of the in silico study were: cantilever position (mesial or distal) and implant connection (external hexagon or morse taper). 100 N vertical load to premolar and 300 N to molar were used to simulate the occlusal force in each model to evaluate the distribution of stresses in implants, abutments, screws and cortical and cancellous bone. Result: The external hexagon (EH) connection showed higher cortical compression stress when compared to the morse taper (MT). For both connections, the molar cantilever position had the highest cortical compression. The maximum stress peak concentration was located at the cervical bone in contact with the threads of the first implant. The prosthetic and abutment screws associated with the molar cantilevers showed the highest stress concentration, especially with the EH connection. Conclusion: Morse taper implant connetions associated with a mesial cantilever showed a more favorable treatment option for posterior mandible rehabilitation.

Introdução: Uma melhor distribuição de tensão em implantes e mini-pilares em próteses parciais fixas implanto-suportadas é essencial na reabilitação em região posterior de mandíbula. Objetivo: Avaliar a influência da posição do cantilever e conexão do implante em uma prótese fixa de três elementos confeccionada totalmente em zircônia através do método de elementos finitos tridimensionais (MEF). Material e método: Foram confeccionados quatro modelos baseados em cortes tomográficos da região posterior da mandíbula com uma prótese parcial parafusada fixada em três fixações personalizadas de zircônia. Os fatores investigados do estudo in sílico foram: posição do cantilever (mesial ou distal) e conexão do implante (hexágono externo ou cone morse). Uma carga de 100 N para a região de pré-molares e de 300 N para a região de molares foi usada para simular a força oclusal em cada modelo para avaliação da distribuição de tensões nos implantes, mini pilares, parafusos e tecido ósseo cortical e medular. Resultado: A conexão hexágono externo apresentou maior concentração de tensão no osso cortical quando comparado ao cone morse. Para ambas conexões, o cantilever distal aumentou a tensão no osso cortical. O pico máximo de tensão foi localizado no osso cervical em contato com as primeiras roscas internas do primeiro implante. Os parafusos protéticos e dos mini-pilares associados ao cantilever distal apresentaram maior concentração de tensão, especialmente na conexão hexágono externo. Conclusão: Conexão do implante cone morse associada ao cantilever mesial apresentou uma opção de tratamento mais favorável para a reabilitação na região posterior de mandíbula.

Influence of crown and hybrid abutment ceramic materials on the stress distribution of implant-supported prosthesis / Influência do material cerâmico das coroas e dos pilares híbridos na distribuição de tensão de próteses implanto-suportadas

Introduction: A new dental implant-abutment design is available with the possibility of improving aesthetic with no compromise of mechanical strength, using perforated CAD/CAM ceramic blocks. Objective: This study evaluated the influence of crown and hybrid abutment ceramic materials combination on the stress distribution of external hexagon implant supported prosthesis. Method: Zirconia, lithium disilicate and hybrid ceramic were evaluated, totaling 9 combinations of crown and mesostructure materials. For finite element analysis, a monolithic crown cemented over a hybrid abutment (mesostructure + titanium base) was modeled and screwed onto an external hexagon implant. Models were then exported in STEP format to analysis software, and the materials were considered isotropic, linear, elastic and homogeneous. An oblique load (30°, 300N) was applied to the central fossa bottom and the system's fixation occurred on the bone's base. Result: For crown structure, flexible materials concentrate less stress than rigid ones. In analyzing the hybrid abutment, it presented higher stress values when it was made with zirconia combined with a hybrid ceramic crown. The stress distribution was similar regarding all combinations for the fixation screw and implant. Conclusion: For external hexagon implant, the higher elastic modulus of the ceramic crowns associated with lower elastic modulus of the hybrid abutment shows a better stress distribution on the set, suggesting a promising mechanical behavior.

Introdução: Um novo design de pilar para implantes dentários está disponível com a possibilidade de melhorar a estética sem comprometer a resistência mecânica, usando blocos cerâmicos perfurados para CAD/CAM. Objetivo: Este estudo avaliou a influência da combinação de diferentes materiais cerâmicos para coroa e para pilar híbrido na distribuição de tensões de prótese sobre implante hexágono externo. Método: Zircônia, dissilicato de lítio e cerâmica híbrida foram avaliados, totalizando 9 combinações de materiais para coroa e mesoestrutura. Para análise de elementos finitos, uma coroa monolítica cimentada sobre um pilar híbrido (mesoestrutura + base de titânio) foi modelada sobre um implante de hexágono externo. Os modelos foram exportados em formato STEP para o software de análise, e os materiais foram considerados isotrópicos, lineares, elásticos e homogêneos. Uma carga oblíqua (30°, 300N) foi aplicada no fundo da fossa central e a fixação do sistema ocorreu na base do osso. Resultado: Para a estrutura da coroa, os materiais flexíveis concentram menos tensão que os rígidos. Ao analisar o pilar híbrido, maiores valores de tensão foram observados quando feito com zircônia combinada com uma coroa de cerâmica híbrida. Em todas as combinações simuladas, a distribuição de tensões foi semelhante para o parafuso de fixação e o implante. Conclusão: Associar um material cerâmico com elevado módulo elástico para a coroa com um material de menor módulo elástico para o pilar híbrido resulta em menor concentração de tensão máxima principal, sugerindo um comportamento mecânico promissor para o sistema hexágono externo.

The effect of heat to remove cement on implant titanium abutment and screw / 대한치과보철학회지

PURPOSE: The purpose of this study was to investigate the effect of heat applied to disintegrate cement on the removal torque value and fracture strength of titanium abutment and abutment screw. MATERIALS AND METHODS: Implants, titanium abutments and abutment screws were prepared for each 20 piece. Implant abutments and screws were classified as the control group in which no heat was applied and the experimental group was heated in a vacuum furnace to 450℃ for 8 minutes and cooled in air. The abutments and screws were connected to the implants with 30 Ncm tightening torque at interval 10 minutes and the removal torque value was measured 15 minutes later. And the fracture strength of abutment screw was measured using universal testing machine. RESULTS: The mean removal torque value was 27.84 ± 1.07 Ncm in the control group and 26.55 ± 1.56 Ncm in the experimental group and showed statistically significant difference (P .05). CONCLUSION: The heat applied for cement disintegration significantly reduced the removal torque value of the abutment screw and did not significantly affect fracture strength of the abutment screw. Therefore, in the case of applying heat to disintegrate cement it is necessary to separate the abutment screw or pay attention to the reuse of the heated screw. However further studies are needed to evaluate the clinical reuse of the heated screw.

Digital evaluation of axial displacement by implant-abutment connection type: An in vitro study

PURPOSE: To measure axial displacement of different implant-abutment connection types and materials during screw tightening at the recommended torque by using a contact scanner for two-dimensional (2D) and three-dimensional (3D) analyses. MATERIALS AND METHODS: Twenty models of missing mandibular left second premolars were 3D-printed and implant fixtures were placed at the same position by using a surgical guide. External and internal fixtures were used. Three implant-abutment internal connection (INT) types and one implant-abutment external connection (EXT) type were prepared. Two of the INT types used titanium abutment and zirconia abutment; the other INT type was a customized abutment, fabricated by using a computer-controlled milling machine. The EXT type used titanium abutment. Screws were tightened at 10 N·cm, simulating hand tightening, and then at the manufacturers' recommended torque (30 N·cm) 10 min later. Abutments and adjacent teeth were subsequently scanned with a contact scanner for 2D and 3D analyses using a 3D inspection software. RESULTS: Significant differences were observed in axial displacement according to the type of implant-abutment connection (P < .001). Vertical displacement of abutments was greater than overall displacement, and significant differences in vertical and overall displacement were observed among the four connection types (P < .05). CONCLUSION: Displacement according to connection type and material should be considered in choosing an implant abutment. When adjusting a prosthesis, tightening the screw at the manufacturers' recommended torque is advisable, rather than the level of hand tightening.

Analysis of risk factors of 19 fractured implants / 中华口腔医学杂志

Objective@#To analyze the incidence and possible risk factors of 19 fractured implants out of 8 468 implants in 3 184 cases.@*Methods@#During the 22-year clinical practice, clinical records of 18 patients with 19 fractured implants in 3 184 cases with 8 468 implants were analyzed to determine the following factors: location of the fractured implants, prosthodontics option, date of implant fracture, dimensions of fractured implants, complications prior to implant fracture and parafunctional habit. An evaluation of fractured implants was performed to identify possible factors that may predispose an implant to a higher risk of fracture.@*Results@#Overall, the average duration of service of the implants was (7.0±4.5) years. Implant fracture occurred in 7 Camlog implants, 7 Nobel replace implants, 3 Ankylos implants and 2 Brånemark implants. No Thommen implant fractures were recorded. Amongst the 19 fractured implants, 8 occurred at the thinnest wall portion of the implant neck, 8 at the end of screw and 3 at the self-tapping thread region. All fractures were observed after functional loading. Furthermore, 9/19 (47.4%) of fractures occurred in the maxilla, indicating similar incidence rates in both arches (P=0.065). Most of fractures (16/19) occurred in the molar region and 18/19 in single implant-supported restorations. Totally 17 cases had received metal occlusal restorations. In 6 cases (35.5%), previous bone destruction apically extending to the level of implant fracture was documented before any clinical signs of fracture. Three fractured implants were removed and simultaneously re-implanted with larger-diameter implants, while the rest of the cases were left to heal, followed by a second-stage surgery.@*Conclusions@#Within the limitation of this analysis, the study demonstrated that appropriate implant-abutment connection design, implant diameter, prosthetic strategy and bone resorption are crucial to the long-term performance of implants. There is no significant difference of fractures rates in both archs.

Comparison of marginal bone loss between internal- and external-connection dental implants in posterior areas without periodontal or peri-implant disease

PURPOSE: The purpose of this retrospective study with 4–12 years of follow-up was to compare the marginal bone loss (MBL) between external-connection (EC) and internal-connection (IC) dental implants in posterior areas without periodontal or peri-implant disease on the adjacent teeth or implants. Additional factors influencing MBL were also evaluated. METHODS: This retrospective study was performed using dental records and radiographic data obtained from patients who had undergone dental implant treatment in the posterior area from March 2006 to March 2007. All the implants that were included had follow-up periods of more than 4 years after loading and satisfied the implant success criteria, without any peri-implant or periodontal disease on the adjacent implants or teeth. They were divided into 2 groups: EC and IC. Subgroup comparisons were conducted according to splinting and the use of cement in the restorations. A statistical analysis was performed using the Mann-Whitney U test for comparisons between 2 groups and the Kruskal-Wallis test for comparisons among more than 2 groups. RESULTS: A total of 355 implants in 170 patients (206 EC and 149 IC) fulfilled the inclusion criteria and were analyzed in this study. The mean MBL was 0.47 mm and 0.15 mm in the EC and IC implants, respectively, which was a statistically significant difference (P < 0.001). Comparisons according to splinting (MBL of single implants: 0.34 mm, MBL of splinted implants: 0.31 mm, P=0.676) and cement use (MBL of cemented implants: 0.27 mm, MBL of non-cemented implants: 0.35 mm, P=0.178) showed no statistically significant differences in MBL, regardless of the implant connection type. CONCLUSIONS: IC implants showed a more favorable bone response regarding MBL in posterior areas without peri-implantitis or periodontal disease.