Cytotoxicity, Morphology and Chemical Composition of Two Luting Cements: An in Vitro Study

Abstract Objective: To assess the cytotoxicity, surface morphology, elemental compositions and chemical characterization of two commonly used luting cement. Material and Methods: The two luting types of cement used were Elite Cement® and Hy-Bond Resiglass®. Freshly mixed (n=6) and set form (n=6) of each cement was placed in medium to obtain extracts. The extract from each sample was exposed to L929 mouse fibroblasts (1x104cells/well). Alamar Blue Assay assessed cell viability. Surface morphology and elemental composition were evaluated using scanning electron microscopy and energy dispersive spectroscopy. The chemical characterization was performed by Fourier Transform Infrared Spectroscopy. One-way ANOVA and post-hoc Tukey analysis were conducted to assess results. Results: Hy-Bond Resiglass® was the more cytotoxic of the two types of cement in both freshly mixed (68.10 +5.16; p<0.05) and set state (87.58 +4.86; p<0.05), compared to Elite Cement® both freshly mixed (77.01 +5.45; p<0.05) and set state (89.39 +5.66; p<0.05). Scanning electron microscopy revealed a more irregular and porous structure in Hy-Bond Resiglass® compared to Elite Cement®. Similarly, intense peaks of aluminium, tungsten and fluorine were observed in energy dispersive spectroscopy in Hy-Bond Resiglass. Conclusion: All these three elements (aluminium, tungsten and fluorine) have cytotoxic potential. The Fourier transform infrared spectroscopy revealed the presence of hydroxyethyl methacrylate in Hy-Bond Resiglass®, which has a cytotoxic potential.

Effect of the action of diamond burs with high speed on the tensile strength of cores cemented with zinc phosphate at different preparation times / Efeito de pontas diamantadas com alta rotação na resistência à tração de núcleos cimentados com fosfato de zinco em diferentes tempos de preparação

Objective: To know the finishing effect, in order to be able to safely proceed with the cores preparation in the daily clinic, without compromising the prosthetic restoration longevity. Methods: This study used 48 human single-rooted premolars, which after the section of its crowns, were endodontically treated, and its root canal prepared 8 mm deep to receive cores casting in cobalt-chrome alloy. Cementing was made with zinc phosphate and the tensile test performed at different preparation times: G1 - without re-preparation after cementation (control); G2 - re-prepared 24 hours after cementation, and G3 - re-prepared 15 minutes after cementation. Results: Statistical analysis showed no significant difference in the tensile strength values in the different groups (p = 0.233), in other words, the core re-preparation 15 minutes or 24 hours after the cementation caused no significant reduction in tensile strength between the core and the root remaining when using the zinc phosphate cement. Conclusion: The metallic core re-preparation cast 15 minutes or 24 hours after cementation caused no significant reduction in tensile strength between the cast metallic core and the root remaining, although in absolute values there was an important difference.

Objetivo: Saber o efeito desse acabamento, para que se possa prosseguir com a preparação desses núcleos na clínica diária de forma segura, sem comprometer a longevidade da restauração protética. Métodos: Utilizou-se neste estudo, 48 pré-molares unirradiculares humanos, que após a secção de suas coroas, foram tratados endodonticamente, e seus condutos radiculares preparados com 8 mm de profundidade para receber núcleos fundidos em liga de cobalto-cromo. A cimentação foi feita com fosfato de zinco e o teste de tração realizado em diferentes tempos de preparação: G1- sem repreparo após a cimentação (controle); G2- repreparados 24 horas após a cimentação e G3- repreparados 15 minutos após a cimentação. Resultados: A análise estatística revelou não haver diferença significativa nos valores de resistência à tração nos diferentes grupos (p = 0,233), ou seja, o repreparo do núcleo após 15 minutos ou 24 horas da cimentação não causou redução significativa na resistência à tração entre o núcleo e o remanescente radicular quando se empregou cimento de fosfato de zinco. Conclusão: o repreparo do núcleo metálico fundido após 15 minutos ou 24 horas da cimentação não causou redução significativa na resistência à tração entre o núcleo metálico fundido e o remanescente radicular, embora em valores absolutos tenha havido uma diferença importante.

Effects of abutment taper on the uniaxial retention force of cement retained implant restorations / Effects of abutment taper on the uniaxial retention force of cement retained implant restorations / Efeito da conicidade do pilar na resistência de união de coroas cimentadas sobre implantes

Aim: The purpose of this study was to evaluate the bond strength of metallic crowns cemented to straight and angled customizable abutments with zinc phosphate. Material and Method: Thirty-nine external hex nalogs and abutments were divided in group S: customizable straight abutment (n = 10), group A17 with 17° angled abutment (n = 10) and group A30 with 30° angled abutment (n = 10) all cemented with zinc phosphate. The metal copings were cemented onto their corresponding metal dies according manufacture guidelines. Data from the all groups were compared with a 1-way ANOVA (?=.05) and Tukey's test. SEM evaluation were performed (n = 3) aiming to investigate microscopic features of the abutment-cement-crown interfaces. Results: The mean force (SD) required to dislodge the crowns in the S, A17 and A30 groups was 357.26 (62.21) N; 251.50 (20.13) N and 276.70 (17.96) N respectively. The Tukey test (p <0.05) revealed a significant statistically differences between the groups (p =.002) and the 17° angled abutment and 30° angled abutment group were statistically similar to each other and different from the group of straight abutments. Zinc phosphate showed an inhomogeneous cement line in SEM analysis. Conclusions: Within the limitations of this study, it can be conclude that the available surface area and convergence of the abutments axial walls of the straight abutments positively influenced bond strength in metallic crowns cemented with zinc phosphate.

Influence of core-finishing intervals on tensile strength of cast posts-and-cores luted with zinc phosphate cement

The core finishing of cast posts-and-cores after luting is routine in dental practice. However, the effects of the vibrations produced by the rotary cutting instruments over the luting cements are not well-documented. This study evaluated the influence of the time intervals that elapsed between the cementation and the core-finishing procedures on the tensile strength of cast posts-and-cores luted with zinc phosphate cement. Forty-eight bovine incisor roots were selected, endodontically treated, and divided into four groups (n = 12): GA, control (without finishing); GB, GC, and GD, subjected to finishing at 20 minutes, 60 minutes, and 24 hours after cementation, respectively. Root canals were molded, and the resin patterns were cast in copper-aluminum alloy. Cast posts-and-cores were luted with zinc phosphate cement, and the core-finishing procedures were applied according to the groups. The tensile tests were performed at a crosshead speed of 0.5 mm/min for all groups, 24 hours after the core-finishing procedures. The data were subjected to one-way analysis of variance (ANOVA) and Tukey's test (α = 0.05). No significant differences were observed in the tensile strengths between the control and experimental groups, regardless of the time interval that elapsed between the luting and finishing steps. Within the limitations of the present study, it was demonstrated that the core-finishing procedures and time intervals that elapsed after luting did not appear to affect the retention of cast posts-and-cores when zinc phosphate cement was used.

Diametral tensile strength and film thickness of an experimental dental luting agent derived from castor oil

The need to develop new dental luting agents in order to improve the success of treatments has greatly motivated research. OBJECTIVE: The aim of this study was to evaluate the diametral tensile strength (DTS) and film thickness (FT) of an experimental dental luting agent derived from castor oil (COP) with or without addition of different quantities of filler (calcium carbonate - CaCO3). MATERIAL AND METHODS: Eighty specimens were manufactured (DTS N=40; FT N=40) and divided into 4 groups: Pure COP; COP 10 percent; COP 50 percent and zinc phosphate (control). The cements were mixed according to the manufacturers' recommendations and submitted to the tests. The DTS test was performed in the MTS 810 testing machine (10 KN, 0.5 mm/min). For FT test, the cements were sandwiched between two glass plates (2 cm²) and a load of 15 kg was applied vertically on the top of the specimen for 10 min. The data were analyzed by means of one-way ANOVA and Tukey's test (α=0.05). RESULTS: The values of DTS (MPa) were: Pure COP- 10.94±1.30; COP 10 percent- 30.06±0.64; COP 50 percent- 29.87±0.27; zinc phosphate- 4.88±0.96. The values of FT (µm) were: Pure COP- 31.09±3.16; COP 10 percent- 17.05±4.83; COP 50 percent- 13.03±4.83; Zinc Phosphate- 20.00±0.12. One-way ANOVA showed statistically significant differences among the groups (DTS - p=1.01E-40; FT - p=2.4E-10). CONCLUSION: The experimental dental luting agent with 50 percent of filler showed the best diametral tensile strength and film thickness.

Comparing the retention of cast posts cemented with three different kinds of cement / Comparação da retenção de pinos fundidos cimentados com três tipos de cimento

Objective: To check and compare the retention of cast posts cemented with three different kinds of cement. Method: Forty five 45 human permanent maxillary incisors were randomly divided into three groups of 15 teeth. Root canals were prepared for the cast posts up to 8.5mm in length. The cast post obtained randomly were cemented with the help of the three cements (Zinc Phosphate, Glass-ionomer and resin modified Glass-ionomer [hybrid] cement). After cementation, the samples were stored in a physiological solution for seven days, after which we concluded the measure of retentive strength with the help of the universal testing machine (Zwick num. 112627, Ulm-Germany). Results: The hybrid cement has the greatest means value for retention and it is 312.90 N. It is followed by the Glass-ionomer cement with 272.40 N, while the Zinc Phosphate has the least, at 312.90 N. The statistical analysis shows that there is a statistical difference in the retention strength between the Zinc Phosphate cement and the Glass-ionomer (p<0.01), between the Zinc Phosphate cement and the hybrid cement (p<0.01). Conclusion: A significant statistical discrepancy was not manifested between the Glass-ionomer cement and the hybrid cement even though the difference in retention strength for these two cements was around 40 N.

Objetivo: Verificar e comparar a retenção de pinos fundidos cimentados com três diferentes tipos de cimento. Método: Quarenta e cinco incisivos superiores permanentes humanos foram divididos aleatoriamente em três grupos de 15 dentes cada um. Os canais radiculares foram preparados para receberem pinos fundidos de até 8.5 mm de comprimento. Os pinos foram cimentados com um dos três tipos de cimentos a seguir: cimento de fosfato de zinco, cimento de ionômero de vidro e cimento de ionômero de vidro modificado por resina (híbrido). Após a cimentação, as amostras foram armazenadas em solução salina durante 7 dias e então submeti das à análise da força de retenção em máquina universal de ensaios (Zwick num. 112627, Ulm-Germany). Resultados: O cimento híbrido apresentou o maior valor médio de retenção (312.90 N), seguido do cimento de ionômero de vidro (272.40 N) e do cimento de fosfato de zinco (312.90 N). A análise estatística mostrou diferença estatisticamente significante nos valores de retenção entre o cimento de fosfato de zinco e o cimento de ionômero de vidro (p<0,01), e entre o cimento de fosfato de zinco e o cimento híbrido (p<0,01). Conclusão: Não houve discrepância significativa entre o cimento de ionômero de vidro e o cimento híbrido, embora a diferença na força de retenção entre os dois materiais tenha sido de aproximadamente 40 N.

Cimentos usados em prótese fixa: uma pesquisa com especialistas em prótese de Porto Alegre / Cements used for fixed prosthodontics: a survey with Porto Alegre specialists

Actually, many dental cements are available to cement fixed prosthesis at dental clinical practice. The aim of this study was to evaluate the cements used to fixed prosthesis by specialists who work at city of Porto Alegre with a questionnaire. A questionnaire with 22 questions was elaborated and applied to professionals registered at Regional Dentistry Council (CRO). From the 225 electable subjects, 39 were excluded. The sample of 186 specialists, 72 weren´t interviewed. The 114 interviewed subjects represented a 61.29% of response rate. The graduate year of 52% of subjects was between 1981 and 2000, and 63% finished the post graduate course after 1991. To final cementation of fixed metal ceramic prosthesis, 65% used zinc phosphate cement. However, to cements metal free fixed prosthesis, 57% used resinous cement. With technological advances at rehabilitation materials, new materials and techniques were developed. However, the zinc phosphate cement is still the first choice to cement metal ceramic prosthesis to Porto Alegre specialists.

Atualmente, diversos cimentos são utilizados para cimentação de próteses fixas na prática clínica odontológica. Sendo assim, o objetivo do presente estudo foi avaliar o uso de cimentos para prótese fixa por especialistas em prótese dentária que atuam no município de Porto Alegre. Para isso, um questionário com 22 perguntas foi elaborado e aplicado a tais profissionais registrados no Conselho Regional de Odontologia. Dentre os 225 indivíduos elegíveis, 39 foram excluídos. Da amostra de 186 especialistas, 72 não foram entrevistados. Os 114 indivíduos entrevistados representaram uma taxa de resposta de 61,29%. O ano de graduação de 52% dos respondentes foi entre 1981 e 2000 e 63% concluíram o curso de pós-graduação após 1991. Para cimentação final de próteses fixas métalo-cerâmicas, 65% dos dentistas usavam cimento de fosfato de zinco. Entretanto, para prótese fixas livres de metal, 57% utilizavam cimento resinoso. Com o avanço da tecnologia em materiais reabilitadores, novos materiais e técnicas foram criados, no entanto, o cimento de fosfato de zinco segue como primeira escolha entre os especialistas para cimentação final de próteses métalo-cerâmicas.

Estudo comparativo in vivo entre o cimento de fosfato de zinco e o resinoso / Comparative study in vivo between the zinc phosphate cement and resin cement

A cimentação da prótese parcial fixa ao dente preparado é um passo relevante, pois é através desta que veda a diminuta área existente entre o elemento artificial e a estrutura dental, protegendo esta última de elementos irritantes de natureza química, física e bacteriana. Este estudo objetivou analisar qualitativamente a colonização bacteriana supercifial do cimento de fosfato de zinco e do cimento resinoso submetidos ao ataque microbiano in vivo por 7, 14, 21 e 30 dias. Verificou-se que, com o passar do tempo, o cimento de fosfato de zinco apresentou, em geral, uma quantidade maior de microorganismos na sua superfície do que o cimento resinoso.

The cementation of the fixed partial prosthesis the prepared tooth is an important step, because it is through this that the small area tetween the artificial element and teeth structure is closed, protecting the it from the chemical, physical and bacterial nature of irritable elements. The study aims at analyzing qualitatively the superficial bacterial colonization of both zinc phosphate and resin cement submitted to microbial attack in vivo during 7, 14, 21 and 30 days. It was verified that, with time, the zinc phosphate cement has, in general, a larger quantity of microorganisms on the surface of the resin cement.

Influência da superfície do preparo dentário e do cimento de fosfato na resistência à tração de copings metálicos / Influence of tooth preparation surface and zinc phosphate cement on the tensile bond strength of metallic copings

Objetivo: Avaliar a resistência à tração de copings de prata-estanho cimentados em dentina humana variando o cimento de fosfato e a superfície do preparo dentário. A hipótese nula foi que a superfície do preparo e o tipo cimento de fosfato não influenciam na resistência à tração dos copings metálicos.Método: Utilizando um torno mecânico, foram realizados preparados padrões para coroas totais em sessenta terceiros molares humanos, extraídos por indicação periodontal, sendo trinta preparos (Gr1) realizados com ponta montada diamantada (Komet, USA) e os outros trinta (Gr2) com broca carbide (Komet, USA). Para cada preparo foram confeccionados copings metálicos, os quais foram cimentados (carga axial: 5kg, tempo: 7 minutos) sobre os respectivos preparos dentários com três diferentes cimentos de fosfato de zinco (n=10): Gr1a/Gr2a- S.S. White, Gr1b/Gr2b - DFL e Gr1c/Gr2c - LS (Vigodent). Após 48 horas (estufa: 370C), os espécimes foram submetidos ao teste de resistência à tração (1mm/min; 50Kgf) em uma máquina de ensaio universal (EMIC). Os dados (Kgf) foram submetidos à análise estatística utilizando os testes ANOVA (dois fatores) e Tukey (5%).Resultados: Os valores obtidos para as condições experimentais foram: Gr1a (20,43±2,4Kgf), Gr1b (23,5±5,6Kgf), Gr1c (33,2±6,3Kgf), Gr2a (25,1±9,5Kgf), Gr2b (27,8±3,6Kgf) e Gr2c (32,5±8,3Kgf). Os resultados demonstraram que o efeito principal superfície do preparo não foi significante (p=0,1), mas analisando o tipo de cimento os grupos Gr1c e Gr2c foram superiores aos demais grupos (p=0,001). A hipótese nula foi rejeitada.Conclusão: O cimento LS gerou valores superiores de resistência à tração, independente do tipo de broca utilizada.

Effect of ultrasonic instrumentation on the bond strength of crowns cemented with zinc phosphate cement to natural teeth: an in vitro study

Several studies have reported the benefits of sonic and/or ultrasonic instrumentation for root debridement, with most of them focusing on changes in periodontal clinical parameters. The present study investigated possible alterations in the tensile bond strength of crowns cemented with zinc phosphate cement to natural teeth after ultrasonic instrumentation. Forty recently extracted intact human third molars were selected, cleaned and stored in physiologic serum at 4°C. They received standard preparations, at a 16º convergence angle, and AgPd alloy crowns. The crowns were cemented with zinc phosphate cement and then divided into four groups of 10 teeth each. Each group was then subdivided into two subgroups, with one of the subgroups being submitted to 5,000 thermal cycles ranging from 55 ± 2 to 5 ± 2°C, while the other was not. Each group was submitted to ultrasonic instrumentation for different periods of time: group 1 - 0 min (control), group 2 - 5 min, group 3 - 10 min, and group 4 - 15 min. Tensile bond strength tests were performed with an Instron testing machine (model 4310). Statistical analysis was performed using ANOVA and Tukey's test at the 5 percent level of significance. A significant reduction in the tensile bond strength of crowns cemented with zinc phosphate and submitted to thermal cycles was observed at 15 min (196.75 N versus 0 min = 452.01 N, 5 min = 444.23 N and 10 min = 470.85 N). Thermal cycling and ultrasonic instrumentation for 15 min caused a significant reduction in tensile bond strength (p < .05).

Assessment of the tensile strength of hexagonal abutments using different cementing agents

The aim of this study was to assess the uniaxial tensile strength after thermal cycling in replicas of CeraOne®abutments (abutment and coping sets), using four types of cements (n = 10). A zinc phosphate cement (Fosfato de Zinco®/ SSW), a resin-modified glass ionomer cement (RelyX®luting / 3M-ESPE), a zinc oxide-eugenol cement (ZOE®/ SSW) and a zinc oxide cement without eugenol (TempBond NE®/ KERR) were used. After cementation, the samples were submitted to thermal cycles (1,000 cycles, 5ºC ± 2º to 55ºC ± 2º) for thirty seconds in each bath. Next, the samples were submitted to the tensile test in a universal test machine (0.5 mm/min). The data were submitted to ANOVA and the Tukey-Kramer test (p < 0.05), and statistically significant difference was found among the cements. The highest tensile strength mean value found was for zinc phosphate cement (33.6 kgf) followed by the resin-modified glass ionomer cement (20.5 kgf), zinc oxide-eugenol cement (8.4 kgf) and the temporary cement (3.1 kgf). Therefore, it was found that the permanent cements presented higher tensile strength, and the temporary cement could be used in situations requiring reversibility and the removal of cemented dental implant-supported prostheses.