Spelling suggestions: "subject:"orthodontic bracket."" "subject:"orthodontics bracket.""
11 |
A comparison of bacterial adherence on standard orthodontic brackets and titanium miniscrew implants an in vivo and in vitro study /Jackfert, Lindsay. January 2008 (has links)
Thesis (M.S.)--West Virginia University, 2008. / Title from document title page. Document formatted into pages; contains ix, 98 p. : ill. (some col.). Vita. Includes abstract. Includes bibliographical references (p. 66-70).
|
12 |
Clinical comparison of two indirect bonding systems on retention rates of orthodontic brackets chemical cured custom base vs. light-cured non-custom base /Cranford, Alexander Davis. January 2009 (has links) (PDF)
Thesis (M.S.)--University of Alabama at Birmingham, 2009. / Title from first page of PDF file (viewed on June 11, 2009). Includes bibliographical references.
|
13 |
Bacterial adherence to orthodontic brackets an in vitro study /Kalaskey, Lawrence J. January 1999 (has links)
Thesis (M.S.)--West Virginia University, 1999. / Title from document title page. Document formatted into pages; contains x, 118 p. : ill. Vita. Includes abstract. Includes bibliographical references (p. 65-72).
|
14 |
Estudo clínico do tempo de fechamento de espaço e do movimento dentário durante a retratação de caninos entre dois tipos de braquetesMonini, André da Costa [UNESP] 13 December 2012 (has links) (PDF)
Made available in DSpace on 2014-06-11T19:33:22Z (GMT). No. of bitstreams: 0
Previous issue date: 2012-12-13Bitstream added on 2014-06-13T20:05:06Z : No. of bitstreams: 1
monini_ac_dr_arafo.pdf: 569037 bytes, checksum: 70156844614f17c25c89142213ee5c2e (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O desenvolvimento tecnológico na fabricação de braquete trouxe consigo a ideia de que a tecnologia empregada no aparelho pode representar aumento na velocidade de movimentação dentária. O propósito deste estudo foi avaliar a taxa de movimentação mensal de caninos e a perda de ancoragem ocorrida durante o movimento de retração de caninos por deslizamento entre dois tipos de braquetes diferentes, um autoligado e outro convencionalmente ligado, bem como diferenças entre os arcos superior e inferior. A amostra consistiu de 25 pacientes biprotusos, portadores de má oclusão de classe I com necessidade de extração de quatro primeiros pré-molares para realização do tratamento ortodôntico, com apinhamento no arco superior e inferior menores que 4mm, idade variando entre 18 anos até 34 anos e sem ausências dentárias sendo facultativa a presença dos terceiros molares. Em todos eles foram colados dois braquetes autoligados, um no canino superior e outro no canino inferior de maneira randomizada e num sistema split-mouth. Os demais dentes receberam braquetes convencionais e tubos nos molares. Os primeiros pré-molares foram extraídos após o alinhamento e nivelamentos dos arcos e 7 a 15 dias após deu-se início à retração dos caninos. Telerradiografias laterais de 45º foram realizadas antes do início da retração e após a completa retração de cada canino. A superposição dos traçados cefalométricos iniciais e após a retração permitiu o cálculo da perda de ancoragem ocorrida e a quantidade de retração para cada canino. A divisão da quantidade de retração pelo tempo decorrido permitiu o cálculo da taxa de movimentação mensal dos caninos. Os resultados demonstraram que não existe diferença na taxa de movimentação mensal dos caninos e nem na perda de ancoragem entre os dois tipos de braquetes... / The technological development in bracket manufacturing brought with it the belief that enhanced technology might translate as faster in tooth movement. The aim of this study was to evaluate the monthly rate of canine movement as well as the rate of anchorage loss during the retraction of canines by sliding mechanics with two different types of brackets: self-ligated and conventional and also, as well as differences between upper and lower arches. The sample comprised 25 biprotusive class I patients with need of four bicuspid extractions for orthodontic treatment, with upper and lower crowding less than 4 mm, age between 18 and 34 years old and no missing teeth except for the third molars. In all of them selfligated brackets were randomly bonded on the upper and lower canines in a split mouth design. The remaining teeth were bonded and banded with conventional brackets. First bicuspids were extracted after leveling and alignment and after 7 to 15 days canine retraction was initiated. Forty-five degree radiographic were taken before retraction and after complete canine retaraction. Cephalometrics tracings before and after canine retraction allowed the measurement of the resultant anchorage loss and the amount of canine retraction. By dividing the amount of canine retraction by it allowed the calculation of the canine movement monthly rate. The results showed that there is no difference between the rate of canine monthly movement and loss of anchorage between the two types of bracket. When arches were compared, upper canines were found to move faster than the lower ones and no difference was found on anchorage loss. It was concluded that canine retraction by sliding mechanics with either brackets occur at the same rate as well as the loss of anchorage of the molars. Upper... (Complete abstract click electronic access below)
|
15 |
Estudo clínico do tempo de fechamento de espaço e do movimento dentário durante a retratação de caninos entre dois tipos de braquetes /Monini, André da Costa. January 2012 (has links)
Orientador: Luiz Gonzaga Gandini Junior / Banca: Ary dos Santos-Pinto / Banca: Dirceu Barnabé Raveli / Banca: Claudio de Góis Nery / Banca: Marcos Augusto Lenza / Resumo: O desenvolvimento tecnológico na fabricação de braquete trouxe consigo a ideia de que a tecnologia empregada no aparelho pode representar aumento na velocidade de movimentação dentária. O propósito deste estudo foi avaliar a taxa de movimentação mensal de caninos e a perda de ancoragem ocorrida durante o movimento de retração de caninos por deslizamento entre dois tipos de braquetes diferentes, um autoligado e outro convencionalmente ligado, bem como diferenças entre os arcos superior e inferior. A amostra consistiu de 25 pacientes biprotusos, portadores de má oclusão de classe I com necessidade de extração de quatro primeiros pré-molares para realização do tratamento ortodôntico, com apinhamento no arco superior e inferior menores que 4mm, idade variando entre 18 anos até 34 anos e sem ausências dentárias sendo facultativa a presença dos terceiros molares. Em todos eles foram colados dois braquetes autoligados, um no canino superior e outro no canino inferior de maneira randomizada e num sistema split-mouth. Os demais dentes receberam braquetes convencionais e tubos nos molares. Os primeiros pré-molares foram extraídos após o alinhamento e nivelamentos dos arcos e 7 a 15 dias após deu-se início à retração dos caninos. Telerradiografias laterais de 45º foram realizadas antes do início da retração e após a completa retração de cada canino. A superposição dos traçados cefalométricos iniciais e após a retração permitiu o cálculo da perda de ancoragem ocorrida e a quantidade de retração para cada canino. A divisão da quantidade de retração pelo tempo decorrido permitiu o cálculo da taxa de movimentação mensal dos caninos. Os resultados demonstraram que não existe diferença na taxa de movimentação mensal dos caninos e nem na perda de ancoragem entre os dois tipos de braquetes... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The technological development in bracket manufacturing brought with it the belief that enhanced technology might translate as faster in tooth movement. The aim of this study was to evaluate the monthly rate of canine movement as well as the rate of anchorage loss during the retraction of canines by sliding mechanics with two different types of brackets: self-ligated and conventional and also, as well as differences between upper and lower arches. The sample comprised 25 biprotusive class I patients with need of four bicuspid extractions for orthodontic treatment, with upper and lower crowding less than 4 mm, age between 18 and 34 years old and no missing teeth except for the third molars. In all of them selfligated brackets were randomly bonded on the upper and lower canines in a split mouth design. The remaining teeth were bonded and banded with conventional brackets. First bicuspids were extracted after leveling and alignment and after 7 to 15 days canine retraction was initiated. Forty-five degree radiographic were taken before retraction and after complete canine retaraction. Cephalometrics tracings before and after canine retraction allowed the measurement of the resultant anchorage loss and the amount of canine retraction. By dividing the amount of canine retraction by it allowed the calculation of the canine movement monthly rate. The results showed that there is no difference between the rate of canine monthly movement and loss of anchorage between the two types of bracket. When arches were compared, upper canines were found to move faster than the lower ones and no difference was found on anchorage loss. It was concluded that canine retraction by sliding mechanics with either brackets occur at the same rate as well as the loss of anchorage of the molars. Upper... (Complete abstract click electronic access below) / Doutor
|
16 |
Avaliação do esmalte dentário antes e após a colagem e descolagem de braquetes ortodônticos / Evaluation of dental enamel before and after fixing and removal of orthodontic brackets ortodônticosJose Hermenergildo dos Santos Junior 13 March 2009 (has links)
O objetivo deste trabalho foi avaliar a quantidade de resina residual após a descolagem de braquetes e a perda e/ou desgaste de esmalte ocorrido durante as fases de: colagem, descolagem e remoção dos remanescentes resinosos, na área do braquete e adjacente. A amostra foi constituída de 150 pré-molares, dividida em dois grupos de acordo com o tipo de material do braquete utilizado: metálico (n=75) e cerâmico (n=75), nas duas primeiras fases do estudo, colagem e descolagem. Os procedimentos de colagem foram realizados de acordo com a International Organization for Standardization (2003), e a descolagem segundo a orientação preconizada pelo fabricante. Na fase de remoção dos remanescentes resinosos foram considerados cinco grupos de acordo com o protocolo de acabamento/polimento e prescrição dos respectivos fabricantes: FF diamantada + Soflex; Pedra Shofu; Dentaurum Carbide; Komet Carbide e Jet Carbide, com auxilio de lupas telescópicas sob a magnificação 3x. A avaliação qualitativa (ARIm e ESI) foi realizada por meio de fotografias digitais (lupa estereoscópica - Olympus SZ61). A avalição quantitativa foi realizada pelo método de medição por Coordenada - Coordinate Measuring Machines (Mitutoyo), mod. Legex CNC 9106 - Perfil de linha. As possíveis diferenças entre os protocolos de acabamento/polimento foram avaliadas pela análise de variância (ANOVA) e pelo teste de comparações múltiplas de Tukey. As quantidades médias de resina residual encontrada na área sob a base do braquete, após acabamento/polimento foram: Diamantada FF + Soflex (10,4 m ±10,5), Pedra Shofu (18,5 m ± 12,1), Dentaurum Carbide (11,2 m ± 11,9), Komet Carbide (9,5 m ± 10,8) e Jet Carbide (22,8 m ± 24,0). E na área adjacente: Diamantada FF + Soflex (14,9 m ± 13,0), Pedra Shofu (22,8 m ±19,5), Dentaurum Carbide (21,4 m ±18,5), Komet Carbide (9,6 m ± 7,7), Jet Carbide (27,8 m ± 24,5). Desta forma, constatou-se que, em geral, os protocolos de acabamento/polimento deixaram maior quantidade de resina residual sobre a área adjacente que na área do braquete, com exceção do protocolo Komet Carbide, que teve desempenho semelhante em ambas as áreas. E as quantidades médias de perda e/ou desgaste do esmalte na área do braquete foram: Diamantada FF + Soflex (-134,9 m ± 56,4), Pedra Shofu ( 39,2 m ± 12,8), Dentaurum Carbide ( 70,5 m ± 27,9), Komet Carbide (-44,8 m ± 14,3) e Jet Carbide ( 68,2 m ± 35,7) na área do braquete, enquanto na área adjacente: Diamantada FF + Soflex (-124,7 m ± 133,1), Pedra Shofu (- 37,9 m ± 25,1), Dentaurum Carbide (- 60,1 m ±32,4), Komet Carbide (-36,6 m ± 19,5) e (Jet Carbide 65,4 m ± 65,0) (Tabela 5.9). Ressalta-se que em ambas as áreas de avaliação, o protocolo (Diamantada FF + Soflex) foi responsável pela maior quantidade de perda e/ou desgaste, diferenciando-se com significância estatística dos demais protocolos. Com base nestes resultados podemos concluir que os protocolos de acabamento/polimento avaliados demonstraram excelente desempenho na remoção dos remanescentes resinosos embora nenhum deles tenha sido capaz de remover totalmente o material de colagem, todos danificaram o esmalte, sendo o protocolo Komet carbide o mais diferenciado. / The objective of this study was to evaluate the quantity of residual resin after removal of brackets and the loss and//or wear-and-tear of enamel occurring during the phases of fixing, detaching and removal of remnant resin in the bracket area and its adjacent. The sample was made up of 150 premolars, divided into two groups in accordance with the type of bracket material used: metal (n=75) and ceramic (n=75), in the two initial phases of study, fixing and removal. Fixing procedures were carried out in accordance with the International Organization for Standardization, (2003), and removal according to orientation advocated by the manufacturer. In the removal of remnant resin phase five groups were considered, all in agreement with the finishing/polishing protocol and prescription of the respective manufacturers: FF diamantada + Soflex; Pedra Shofu; Dentaurum Carbide; Komet Carbide and Jet Carbide, and with the aid of telescopic magnifying glass of three-fold magnification Qualitative evaluation (ARIm and ESI) was done by means of digital photographs(stereoscopic magnifying glass Olympus SZ61). Quantitative evaluation was conducted using the coordinate medication method - Coordinate Measuring Machines (Mitutoyo), mod. Legex CNC 9106 - line profile. Possible differences between finishing/polishing protocols were evaluated via variance analysis (ANOVA), and by Tukey Multiple Comparison test. Median quantities of residual resin found in the region below the base of the bracket, following finishing/polishing were: Diamantada FF + Soflex (10,4 m ±10,5), Pedra Shofu (18,5m ± 12,1), Dentaurum Carbide (11,2 m ± 11,9), Komet Carbide (9,5 m ± 10,8) and Jet Carbide (22,8 m ± 24,0). In this way, it was confirmed that finishing/polishing protocols, in general, left the major part of residual resin below the adjacent area than in the bracket area, with the exception of Komet Carbide protocol, displaying similar performance in both areas Median quantities of loss and/or wearand- tear of enamel in the bracket area were: Diamantada FF + Soflex (-134,9 m ± 56,4), Pedra Shofu ( 39,2 m ± 12,8), Dentaurum Carbide ( 70,5 m ± 27,9), Komet Carbide (-44,8 m ± 14,3) and Jet Carbide ( 68,2 m ± 35,7) in bracket area, while in adjacent area: Diamantada FF + Soflex (-124,7 m ± 133,1), Pedra Shofu (- 37,9 m ± 25,1), Dentaurum Carbide (- 60,1 m ±32,4), Komet Carbide (-36,6 m ± 19,5) and (Jet Carbide 65,4 m ± 65,0) (Table 5.9) Standing out in both areas of evaluation, protocol (Diamantada FF + Soflex) was responsible for the major quantity of loss and /or wear and tear, differentiating itself from the other protocols by significant statistics. Based on these results, we can conclude that the finishing/polishing protocols evaluated, displayed excellent performance in the removal of remnant resin, although none have totally been capable of removing fixing material, and all damaged the enamel, with Komet protocol being the most differentiated.
|
17 |
The Effect of Wire Fixation Methods on the Measured Force Systems of a T-Loop Orthodontic SpringGregg, Joseph R. January 1997 (has links)
Indiana University-Purdue University Indianapolis (IUPUI) / Ideal orthodontic springs are able to provide a controlled moment-to-force (M/F) ratio and a low load deflection rate. A great deal of research has gone into describing force systems generated by orthodontic springs. Most studies investigating the force system generated by T-loops have used rigid fixation for the spring ends. This is practical for laboratory studies, but it does not truly represent clinical situations in which orthodontic brackets are used to anchor spring ends. Results from laboratory studies have been applied to clinical situations without regard to what effect, if any, the method of end fixation may have.
It is the goal of this study to determine the effects of spring fixation on generated force systems. The springs were held by rigid fixation and bracket ligation with either elastomeric or steel ligature ties. Comparison of these fixation methods was made by testing T-loops of different dimensions, with and without heat treatment at various activation distances. In theory, the wire is ligated rigidly against the bracket, so that the combination acts as a single unit by rigid fixation. Thus, there should be no difference between the generated force systems when spring ends are held by rigid fixation, or when they are held in place with orthodontic brackets and ligated by either elastomeric or steel ligature ties. However, the results indicate that are significant differences among the methods of fixation for each spring variation and heat treatment. The rigid fixation method consistently produced smaller moments and M/F ratios for all springs with every activation and heat treatment combination.
|
18 |
Evaluation of Tensile Bond Strength, Fluoride Release, Hardness, and Solubility of a Fluoride Containing Adhesive ResinBrandt, Marybeth January 1994 (has links)
Indiana University-Purdue University Indianapolis (IUPUI) / Direct bonding of orthodontic brackets often results in decalcification of tooth structure surrounding bracket sites. Glass ionomer cements, while typically leaching fluoride over time, often exhibit a significantly lower bond strength. Fluoride-containing resins generally release high concentrations of fluoride for a short time, then cease to release any significant amount. The purpose of this study was to evaluate the tensile bond strength, fluoride release, hardness, solubility, and sorption of a newly formulated fluoride containing resin. The experimental resins were prepared with 5% and 7.5%
fluoride (F-) monomer, and were compared to a fluoride-free control adhesive (Rely-a-Bond Phase II™, Reliance Orthodontics Inc ., Itasca, Ill .). To evaluate tensile bond strength, orthodontic brackets were bonded to bovine teeth and debonded using an lnstron machine. Fluoride release was tested using resin disks stored in deionized water. The fluoride content of the water was determined with an ion-specific electrode. Hardness, solubility, and sorption were tested using disks made of each material. Comparison of experimental and control resins by ANOVA followed by General Linear Models multiple comparisons revealed the control to show a statistically significant difference (p<.0001) for tensile bond strength. Experimental Control 5%F- 7.5%F- Peak Stress (MPa) 4.48±0.65 3.83±0.76 5.31±0.97. Fluoride continued to be released from the experimental resins (5% and 7.5% F-) at 18 days. The control was significantly harder than either of the experimental resins at 1 hour, 24 hours, 1 week, and 1 month (p<.0001). The 5% F- resin exhibited slight solubility (0.10 percent), while the 7.5%F- resin and the control exhibited very little solubility (0.01 percent). Phase II™ exhibited significantly lower sorption at 21 days (0.60 percent, p<.001) than either the 5%F- resin (1.69 percent) or the 7.5%F- resin (1.63 percent). These results indicate that while the experimental resin had lower bond strength, lower hardness, and higher sorption than the control, measurable fluoride was released from the experimental resins for up to 18 days. Further testing is indicated to determine the clinical acceptability of this adhesive.
|
19 |
Effect of Adherent Contour on Orthodontic Tensile Bond StrengthAlvarez, Edwin January 2001 (has links)
Indiana University-Purdue University Indianapolis (IUPUI) / Many factors may affect orthodontic bond strength study results. An important variant to consider is the bonding surface contour. Contour alters the proximity of adherent surfaces, the surface area available for adhesion, and the stress distribution. It was the purpose of this study to determine if bracket base or enamel contour affect in vitro bond strengths. Orthos Mini-Diamond (ORMCO Corp.) .0 018" slot central incisor brackets with flattened or unaltered curved bases were bonded (System 1 + self cure resin cement by ORMCO, Corp.) to unaltered and flattened bovine central incisors. Bond strengths were determined by debonding on a Bionix 858 (MTS System Corp.) testing machine. The results showed that unaltered bracket bases bonded on unaltered enamel surfaces (the closest approximation to a clinical situation) had the significantly (p< 0.0002) lowest tensile bond strength among the three combinations. The adhesive remnant index evaluation demonstrated that unaltered bracket base/ unaltered enamel surface (Group II) had significantly higher ARI (less adhesive remaining on enamel) than any of the other groups. A negative correlation between ARI scores and mean bond strength was found. There was not a significant difference between flattened bracket base / flattened enamel surface (Group I) and unaltered bracket base/ flattened enamel surface. The results suggest that the surface convexity and texture of enamel are important variables that can affect bond strength tests results. Standardization of testing protocols and control of the different variables that can affect bond strength are important factors in the testing of orthodontic brackets.
|
20 |
Bond strength of metal orthodontic brackets to all ceramic crownsIsmail, Moosa January 2016 (has links)
Magister Scientiae Dentium - MSc(Dent) / Aim: The aim of this study was to evaluate, in-vitro, the shear bond strength (SBS) and the resultant failure pattern after debonding of metal orthodontic brackets bonded with TransbondTM XT adhesive resin cement and RelyXTM Unicem 2 self-adhesive resin cement to pre-treated (35% ortho-phosphoric acid and silane coupling agent application) IPS eMax and porcelain veneered zirconia crowns. Material and methodology: A Typhodont maxillary lateral incisor was used and prepared in a conventional manner to receive a full ceramic crown. A CAD (computer aided design)/ CAM (computer aided manufacturing) machine was used to scan the prepared tooth and manufacture 40 IPS eMax crowns and 40 porcelain veneered zirconia crowns. Half the number of IPS eMax crown specimens (ie. 20) and half the number of porcelain veneered zirconia crown specimens (ie. 20) were thermocycled (ie. to mimic thermal changes which occur in the mouth), from 5 to 55o for 500 cycles as recommended by the International Organization for Standardization (ISO 6872, 2008). The remaining 20 IPS eMax crown specimens and 20 porcelain veneered zirconia crown specimens remained new and unexposed to thermal changes. The facial surfaces of all the thermocycled and non-thermocycled crown specimens were then etched. Etching of all the ceramic bonding surfaces was performed by the application of 35 per cent ortho-phosphoric acid liquid for 2 minutes, followed by a thin layer of a ceramic primer. A lateral incisor metal bracket with a bracket base area of 9mm2 (as confirmed by the manufacturer) was bonded to each of the etched and silane treated ceramic crown specimens and separated in the following manner: Group 1: (10 thermocycled, etched and silane treated IPS eMax and 10 thermocycled, etched and silane treated porcelain veneered zirconia crown specimens) RelyX™ Unicem 2 self-adhesive resin cement was used to bond the bracket to the ceramic crown specimens, Group 2: (10 thermocycled, etched and silane treated IPS eMax and 10 thermocycled, etched and silane treated porcelain veneered zirconia crown specimens) Transbond™ XT light cure adhesive primer was first applied onto the bonding surface of the crowns and then Transbond™ XT adhesive resin was used to bond the bracket to the ceramic crown specimens, Group 3: (10 non-thermocycled, etched and silane treated IPS eMax and 10 non-thermocycled, etched and silane treated porcelain veneered zirconia crown specimens) RelyX™ Unicem 2 self-adhesive resin cement was used to bond the bracket to the ceramic crown specimens, Group 4: (10 non-thermocycled, etched and silane treated IPS eMax and 10 non-thermocycled, etched and silane treated porcelain veneered zirconia crown specimens) Transbond™ XT light cure adhesive primer was first applied onto the bonding surface of the crowns and then Transbond™ XT adhesive resin cement was used to bond the bracket to the ceramic crown specimens. After bonding all samples were stored in distilled water for 24 hours before being submitted to the shear bond strength test. Debonding forces in Newtons (N) was determined by using a shear testing machine and converted into Mega Pascals (MPa). Results: The results after debonding were compared. The mean shear bond strength for RelyXTM Unicem 2 self-adhesive resin cement bonded to the all ceramic non-thermocycled crowns (Group 3) ranged from a low of 5.1 MPa (45.5 Newtons) when brackets were bonded to the IPS eMax crowns to a high of 5.8 MPa (51.9 Newtons) when brackets were bonded to the porcelain veneered zirconia crowns. The mean shear bond strength for Transbond XT adhesive resin cement bonded to the all ceramic non-thermocycled crowns (Group 4) ranged from a low of 6.4 MPa (57.3 Newtons) when brackets were bonded to the porcelain veneered zirconia crowns to a high of 8.1 MPa (72.7 Newtons) when brackets were bonded to the IPS eMax crowns. The side by side Box-and-Whisker plots of the shear bond strengths show wide and overlapping dispersions of the crown/adhesive resin combinations which consequently lessen the probability of significant differences between the crown/adhesive resin combinations in all 4 groups. According to the Kruskal-Wallis test (p < 0.05), and the Bonferroni Test the non-thermocycled crown/adhesive resin combinations do not differ significantly. Study of the mean ARI (Adhesive Remnant Index) values for the non-thermocycled crown/adhesive combinations shows that brackets bonded with Rely-XTM Unicem 2 to non-thermocycled porcelain veneered zirconia crowns failed entirely at the ceramic/adhesive interface and for all the other non-thermocycled ceramic/adhesive combinations most of the failures of the bond (70%) occurred at the bracket/adhesive interface, ie. cohesive fractures within the composite resin. No cohesive fractures of the porcelain crowns were noted. The results of the thermocycled groups (Group 1 and Group 2) show the TransbondTM XT/non-thermocycled IPS eMax crown combination yielded the highest overall mean shear bond strength of 8.1 MPa (72.7 Newtons) but dropped to a mean shear bond strength of 5.1 MPa (46.1 Newtons) (36.4% drop in shear bond strength) when the crowns were thermocycled prior to bonding. The TransbondTM XT/non-thermocycled porcelain veneerd zirconia crown combination yielded the second highest overall mean shear bond strength of 6.4 MPa (57.3 Newtons) and dropped to a mean shear bond strength of 5.1 MPa (45.8 Newtons) (19.3% drop in shear bond strength) when the crowns were thermocycled prior to bonding. The RelyXTM Unicem 2/non-thermocycled porcelain veneered zirconia crown combination yielded the third highest overall mean shear bond strength of 5.8 MPa (51.9 Newtons) but dropped significantly to a mean shear bond strength of 3.2 MPa (29.1 Newtons) (a significant 43.8% drop in shear bond strength) when the crowns were thermocycled prior to bonding. Lastly, the RelyXTM Unicem 2/non-thermocycled IPS eMax crown combination yielded the fourth highest mean shear bond strength of 5.1MPa (45.5 Newtons) but dropped to a mean shear bond strength of 4.9 MPa (44.5 Newtons) (a drop in shear bond strength of only 3%) when the crowns were thermocyled prior to bonding. Relaxing the significance level (p-value) somewhat demonstrates the negative influence of thermocycling on the shear bond strength of the crown/adhesive combinations. The non-thermocycled all ceramic crown/adhesive combinations showed mean ARI values of between 1.3 and 2.1 indicating cohesive fractures within the composite resin and efficient bonding of the adhesive material to the porcelain surface. However, all the thermocycled all ceramic crown/adhesive treatment combinations showed mean ARI values of between 0 and 0.8 indicating a bond failure between adhesive and porcelain and highlighting the negative influence of thermocycling on bond strength of both adhesive resin cements. Conclusion: Within the limitations of this study, it can be concluded that: 1.There was no significant difference in the shear bond strengths of metal orthodontic brackets bonded with RelyXTM Unicem 2 self-adhesive resin cement and metal orthodontic brackets bonded with TransbondTM XT adhesive resin cement to IPS eMax and porcelain-veneered zirconia crowns which were conditioned with 35 % phosphoric acid and a silane coupling agent. 2. Conditioning the porcelain surface with 35% phosphoric acid and a silane coupling agent (which is safer to use than Hydrofluoric acid) is sufficient for bonding metal orthodontic brackets to all ceramic crowns, and should make it simpler for clinicians to remove the remaining adhesive from the porcelain surface after debonding. 3. The negative influence of thermocycling prior to bonding can be seen on shear bond strength values. 4. Most of the failures of the bond occurred at the ceramic/adhesive interface and cohesive fractures within the composite resin. No cohesive fractures of the porcelain crowns were noted.
|
Page generated in 0.0525 seconds