Evaluation of Self-Adhering Flowable Composites on Repeated Bracket Bonding Process: An In Vitro Study

ABSTRACT@#Duration of orthodontic treatment becomes major concern. The present study compared shear bond strength (SBS) and adhesive remnant index (ARI) values of different adhesive systems with different application methods on rebonding process of retrieved orthodontic brackets. Eighty premolar teeth were equally divided into five groups. Transbond XT (TXT) which belongs to total-etch system was used in Group 1 as the control group. Nova Compo-SF (NC) and Vertise Flow (VF) (Kerr Dental, Italy) which are self-adhering flowable composites were used in Group 2 (NC+etch) and Group 3 (VF+etch) respectively with additional etching before application. Group 4 (NC) and Group 5 (VF) were used by following instructions of each brand. The brackets were debonded with a bracket removing plier and rebonded with the same procedures after sandblasting of the bracket and surface cleaning of the enamel. SBS and ARI were measured for each sample. Comparison between all groups was performed by Kruskal-Wallis test and chisquare test. The highest SBS was observed in NC+etch (median = 11.44, mean = 13.49±9.42), followed by NC (median = 10.17, mean = 11.35±6.55), TXT (median = 6.36, mean = 8.06±6.33), VF+etch (median = 5.68, mean = 6.75±4.58), and VF (median = 2.62, mean = 2.92±2.57), respectively. ARI 1 was observed in 81.3% of TXT whereas 62.5% of NC+etch. ARI 1, 2, and 3 were equally distributed in VF+etch group (31.3%). ARI 5 was observed in 37.5% of NC and 62.5% of VF. Analyses referred to statistically significant differences between five groups regarding both SBS and ARI (p < 0.001). As NC showed the highest SBS on rebonding process, it can be a promising alternative to TXT which is the gold standard.

Avaliação do esmalte dentário após recolagens de bráquetes metálicos e cerâmicos / Evaluation of dental enamel after rebonding of metal and ceramic brackets

Na descolagem de bráquetes ortodônticos pode ocorrer a perda de esmalte na interface adesivo-esmalte. O objetivo deste estudo foi avaliar os possíveis danos à superfície do esmalte com recolagens de bráquetes metálicos e cerâmicos novos por meio da resistência adesiva ao cisalhamento (RAC), da análise do índice de adesivo remanescente (IAR), da avaliação da rugosidade de superfície (RA) e pela análise de microscopia eletrônica (MEV). Foram usados 120 pré-molares, divididos aleatoriamente em 4 grupos de 30 dentes: CS (Controle Saliva); CA (Condicionamento Ácido); M (Metálico) e C (Cerâmico). Foram colados 120 bráquetes metálicos e 120 cerâmicos, para os grupos M e C, em quatro tempos. Os ensaios mecânicos foram realizados em máquina SHIMADZU, na velocidade 0,5 mm/min. Na avaliação da RAC, o ANOVA a dois critérios demonstrou não haver diferenças (p= 0,052) entre os grupos. Na avaliação do IAR, o teste U de Mann-Whitney demonstrou diferença entre os grupos (p< 0,001), onde o grupo cerâmico exibiu escores mais altos que o metálico. Para a rugosidade, o ANOVA a um critério demonstrou que o grupo M apresentou maior RA (p< 0,001). O teste de Tukey demonstrou que os grupos M e C, após o polimento com discos Sof-Lex, exibiram valores de rugosidade inferiores aos demais grupos. Conclui-se que na remoção de bráquetes metálicos ou cerâmicos e da resina remanescente existe maior risco de danos ao esmalte nas recolagens sucessivas. O polimento com discos Sof-Lex promoveu superfície com maior lisura do esmalte.

Debonding of orthodontic brackets may cause enamel surface loss primarily at the adhesive-enamel interface. The purpose of the present study was to evaluate by means of shear bond strength (SBS), adhesive remnant index (ARI), assessment of surface roughness and electron microscope analysis, the possible damages at enamel surface with repeated rebonding of new metallic and ceramic brackets. One hundred and twenty human premolars were randomly divided into 4 groups of 30 premolars each: CS (Saliva Control); CA (Acid Etching); M (Metal); C (Ceramic). For CA group, 4 repeated acid conditionings were performed. One hundred and twenty metallic and ceramic brackets, for groups M and C, were bonded and rebonded respectively at 4 stages. Mechanical trials were obtained with a SHIMADZU testing machine at 0.5 mm/min cross-speed. The SBS results were statistically tested with ANOVA, and no statistically significant differences (p=0.052) were observed. The ARI was evaluated by Mann-Whitney test, which demonstrated that there was a statistically significant difference between metallic and ceramic brackets (p<0.001). The ceramic group exhibited higher statistically significant scores for ARI than the metallic group. The roughness assessment was made with one-way ANOVA, that showed statistically significant differences between groups (p<0.001). Tukey´s test has demonstrated that the M and C groups that were polished with SofLex discs had statistically significant lower roughness values as compared to other groups. Polishing with Sof-lex discs, lead to increased smoothness of enamel surfaces.

Resistência adesiva após colagem e recolagem de bráquetes: um estudo in vitro / Bond strength after bonding and rebonding of brackets: an in vitro study

A busca por um material adesivo para recolagem de bráquetes com adesão adequada desperta interesse ao ortodontista. A resina fotopolimerizável ReBond® foi introduzida na Ortodontia com esta finalidade. Objetivos: Avaliar e comparar o desempenho in vitro do ReBond® com a resina Transbond XT® na recolagem de bráquetes metálicos. Materiais e Métodos: Noventa incisivos inferiores bovinos foram divididos em 3 grupos (n=30): Grupo I: bráquetes colados com resina Transbond® e colagem de novos bráquetes com resina Transbond®; Grupo II: bráquetes colados com resina Transbond® e recolados com resina Rebond®; Grupo III: bráquetes colados e recolados com resina Transbond®. Os corpos de prova foram submetidos ao teste de cisalhamento na máquina de ensaio universal DL 500 (EMIC). Os valores obtidos foram analisados estatisticamente e apresentaram distribuição normal (ANOVA e TUKEY-HSD). Resultados: Os resultados evidenciaram existir diferença estatisticamente significante entre grupos e en¬tre colagem/recolagem dos bráquetes. A força de colagem inicial demonstrou ser sempre superior à força de recolagem, em todos os grupos experimentais. Conclusões: A força de recolagem dos bráquetes com Rebond® e Transbond® apresentaram forças de adesão adequadas ao uso clínico...

The search for an adhesive material for satisfactory rebond of brackets awakens interest to the orthodontist. The ReBond® fotopolimerizable resin was introduced in Orthodontics with this purpose. Objectives: To assess and compare the performance of in vitro ReBond® with Transbond XT® resin of metallic orthodontic brackets in rebonding. Materials and Method: Ninety bovine lower incisors were divided into 3 groups (n = 30): Group I: brackets bonded with Transbond® resin and bond of new brackets with Transbond® resin; Group II: brackets bonded with Transbond® resin and rebonded with Rebond® resin; Group III: brackets bonded and rebonded with Transbond® resin. Samples were submitted to a shear test in a universal testing machine DL 500 (EMIC). Data were statistically analyzed and showed normal distribution (ANOVA and TUKEY-HSD). Results: The results showed significant difference between groups and between bond/rebond of brackets. The initial bond strength was always higher than the rebond strength in all experimental groups. Conclusions: The strength of rebonding of the brackets rebonded with Rebond® and Transbond® was adequate to the appropriate clinical use...

Rebonding of unused brackets with different orthodontic adhesives

OBJECTIVE: To compare in vitro shear bond strength (SBS) of different orthodontic adhesives in bonding and repeatedly rebonding metal brackets, and to evaluate the bond failure site with the adhesive remnant index (ARI). METHODS: Specimens consisted of 90 extracted human first premolars, randomly divided into three groups (n=30). The adhesives Alpha Plast (AP), ConciseTM (CO) and TransbondTM XT (TB) were used in each group. Three SBS tests were performed, i.e., one at T0 (initial) and the other two at T1 and T2 (first and second rebondings, respectively), observing a 24-hour interval. The tests were performed in a Shimadzu AG-I (10kN) SBS testing machine, at a speed of 0.5 mm/min. RESULTS: SBS data were subjected to ANOVA, Tukey's test and Bonferroni test (p<0.05). For the ARI, the Kruskal Wallis test was performed, followed by the Dunn test. The results revealed that at T0 groups AP and CO showed SBS values that were near, but above TB values; and at T1 and T2, the highest SBS values were observed for the AP group, followed by the CO and TB groups. CONCLUSION: Statistically significant differences were found in SBS between groups AP, CO and TB during bonding and repeated rebondings of unused metal brackets, with group AP achieving the highest SBS value. Regarding ARI, adhesive AP exhibited bond failure at the enamel-adhesive interface, with a higher enamel fracture frequency.

Influence of rebonding procedures on microleakage of composite resin restorations / 대한치과보존학회지

During a composite resin restoration, an anticipating contraction gap is usually tried to seal with low-viscosity resin after successive polishing, etching, rinsing and drying steps, which as a whole is called rebonding procedure. However, the gap might already have been filled with water or debris before applying the sealing resin. We hypothesized that microleakage would decrease if the rebonding agent was applied before the polishing step, i.e., immediately after curing composite resin. On the buccal and lingual surfaces of 35 extracted human molar teeth, class V cavities were prepared withthe occlusal margin in enamel and the gingival margin in dentin. They were restored with a hybrid composite resin Z250 (3M ESPE, USA) using an adhesive AdperTM Single Bond 2 (3M ESPE). As rebonding agents, BisCover LV (Bisco, USA), ScotchBond Multi-Purpose adhesive (3M ESPE) and an experimental adhesive were applied on the restoration margins before polishing step or after successive polishing and etching steps. The infiltration depth of 2% methylene blue into the margin was measured using an optical stereomicroscope. The correlation between viscosity of rebonding agents and mciroleakage was also evaluated. There were no statistically significant differences in the microleakage within the rebonding procedures, within the rebonding agents, and within the margins. However, when the restorations were not rebonded, the microleakage at gingival margin was significantly higher than those groups rebonded with 3 agents (p < 0.05). The difference was not observed at the occlusal margin. No significant correlation was found between viscosity of rebonding agents and microleakage, except very weak correlation in case of rebonding after polishing and etching at gingival margin (r = -0.326, p = 0.041).

Shear bond strength of rebonded ceramic brackets / 대한치과교정학회지

OBJECTIVE: The purpose of this study was to evaluate the shear bond strength of rebonded ceramic brackets according to each condition and find an appropriate method to rebond ceramic brackets with proper shear bond strength in clinical practice. METHODS: The study consisted of 12 experimental groups, according to the types of brackets, debonding methods, and treatment methods of the bracket base. Shear bond strength was measured, and adhesive residues left on the tooth surface were assessed. The base of the bracket was examined under scanning electron microscopy. RESULTS: The shear bond strength of the monocrystalline ceramic bracket group was significantly higher than thatof the polycrystalline bracket group with only sandblasting (p 0.05). The shear bond strength of the sandblasted/silane group was significantly higher than that of the selectively grinded group with a low-speed round bur and the sandblasted only group (p < 0.001). The retentive structure was more presented in groups where laser was applied than in groups where shear force was applied to debond brackets prior to rebonding. The bracket bases which were treated before rebonding presented smoother surfaces than new brackets. CONCLUSIONS: Shear bond strength could be increased by applying a silane coupling agent after sandblasting before rebonding. Also, the bond strength of the selectively grinded group with a low-speed round bur and the sandblasted group showed acceptable bond strength for clinical orthodontic treatment.

Shear bond strength of rebonded orthodontic bracket with flowable resin / 대한치과교정학회지

This study was performed to evaluate clinical practicality of the rebonding method with flowable resin without the removal of the residual resin on the debonded teeth and debonded bracket base after debonding. The samples of the control group (group I) were rebonded with Transbond XT(R) using the usual rebonding method after the residual resin was removed. At experimental group, the brackets were rebonded with Transbond XT(R) (group II) and CharmFil Flow(R) (group III) without removal of residual resin which is the possibility becoming the index for rebonding to similar position with initial bonding. The shear bond strength of the each group was measured. Patterns of bonding failure were evaluated with modified ARI score, and the shear bond strength according to patterns of bonding failure at experimental group was compared. Between the control group (6.51 +/- 1.21 MPa) and the group II rebonded with Transbond XT(R) (6.30 +/- 1.01 MPa) did not have significantly difference in the shear bond strength (p = 0.534), and the shear bond strength of group II was significantly lower than the group III rebonded with CharmFil Flow(R) (7.29 +/- 1.54 MPa) (p = 0.009). At control group, there was not large difference in distribution of bonding failure pattern. But at experimental group, bond failure did not occur in interface between the resin-enamel. and bond failure between the resin-bracket, within the resin was distributed similarly. There was not significantly difference in the shear bond strength according to patterns of bonding failure at experimental group (p > 0.05). The result of this study showed that the method suggested in this study and flowable resin as rebonding adhesive could be useful in clinically.