ABSTRACT
ABSTRACT Objective: To evaluate, in-vitro, the change in crown inclination that occurs during orthodontic leveling and alignment using different archwire-bracket-ligation combinations. Materials and Methods: Four archwire types were tested: (1) 0.012-in stainless steel and (2) 0.0155-in stainless steel multi-stranded, (3) 0.012-in nitinol Orthonol® and (4) 0.012-in nitinol Thermalloy®. Combinations with five types of 0.022-in slot orthodontic brackets were tested: SmartClipTM and Time3® self-ligating brackets, Mini-Taurus® and Victory SeriesTM conventional brackets, and Synergy® conventional-low friction bracket. Conventional brackets were ligated with both stainless steel and elastomeric ligatures. The simulated malocclusion comprised 2.0mm gingival and 2.0mm labial displacements of a maxillary right central incisor. Rotation around the Y-axis (representing labio-palatal inclination) was measured for the different archwire-bracket-ligation combinations. Results: The largest rotation was measured whith Orthonol® and Thermalloy® wires when combined with SmartClipTM brackets (8.07±0.24º and 8.06±0.26º, respectively) and with Synergy® brackets ligated with stainless steel ligatures (8.03±0.49º and 8.0±0.37º, respectively). The lower rotation was recorded when Thermalloy®, multi-stranded, and Orthonol® wires were ligated with elastomeric rings to Mini-Taurus® brackets (1.53±0.18º, 1.65± 0.23º and 1.70±0.28º, respectively) and to Victory SeriesTM brackets (1.68± 0.78º, 2.92± 1.40º and 1.74±0.46º, respectively). Conclusions: All archwire-bracket-ligation combinations produced lingual crown inclination; however, lower changes were observed when the conventional brackets were ligated with elastomeric rings. The multi-stranded archwire produced less rotation with nearly every bracket-ligation combination, compared to the other archwires. The effect of the archwire-bracket-ligation combination on tooth inclination during leveling and alignment should be considered during planning treatment mechanics.
RESUMO Objetivo: Avaliar, in vitro, as mudanças na inclinação das coroas dentárias que acontecem durante o alinhamento e nivelamento usando diferentes combinações de arcos/braquetes/ligaduras. Material e Métodos: Foram usados quatro tipos de arcos ortodônticos: (1) 0,012" de aço inoxidável, (2) 0,0155" de aço multifilamentado, (3) Orthonol® 0,012" de nitinol e (4) Thermalloy® 0,012" de nitinol. Esses arcos foram combinados com cinco tipos de braquetes ortodônticos com slot 0,022": braquetes autoligáveis SmartClipTM e Time3®, braquetes convencionais Mini-Taurus® e Victory SeriesTM, e braquetes convencionais de baixo atrito Synergy®. Os braquetes convencionais receberam ligaduras de aço ou elastoméricas. A má oclusão simulada foi composta por um deslocamento do incisivo central superior direito em 2 mm para a cervical e 2 mm para a vestibular. A rotação ao redor do eixo Y (representando a inclinação vestibulolingual) foi medida para as diferentes combinações de arco/braquete/ligadura. Resultados: A maior rotação foi medida quando os arcos Orthonol® e Thermalloy® foram usados com os braquetes SmartClipTM (8,07±0,24º e 8,06±0,26º, respectivamente) e com os braquetes Synergy® com ligaduras metálicas (8,03±0,49º e 8,0±0,37º, respectivamente). A menor rotação foi vista quando os arcos Thermalloy®, multifilamentado e Orthonol® foram presos por ligaduras elastoméricas aos braquetes Mini-Taurus® (1,53±0,18º, 1,65±0,23º e 1,70±0,28º, respectivamente) e aos braquetes Victory SeriesTM (1,68±0,78º, 2,92±1,40º e 1,74±0,46º, respectivamente). Conclusões: todas as combinações arco-braquete-ligadura produziram inclinação palatina da coroa. Entretanto, as menores mudanças foram observadas quando os braquetes convencionais receberam ligaduras elastoméricas. O arco multifilamentado produziu menor rotação com quase todas as combinações braquete-ligadura, em comparação aos outros arcos. O efeito da combinação arco-braquete-ligadura na inclinação dentária durante o alinhamento e nivelamento deve ser considerado durante o planejamento da mecânica dos tratamentos.
ABSTRACT
Objective: The aim is to evaluate changes of smile and gingival line after intrusion of maxillary incisors using mini-implant anchorage system or conventional accentuated compensating curve archwire. Materials and Methods: Twenty participants having deep overbite with age ranged from 18 to 24 years were enrolled in this study and were divided into two groups of 10 each. Intrusion of maxillary incisors was performed using mini-implant anchorage system in group 1 and by conventional accentuated compensating curve archwire in group 2. For each participant, lip position, dental and skeletal measurements related to the gingival line were recorded from standardized photographs and cephalometric analyses. Statistical analyses including t-test and Chi-square were used to evaluate differences between groups. Results: There was an improvement of smile arc (consonance) from 30% smile consonance pretreatment to 90% consonance postintrusion in group 1, but the change was insignificant in Group 2. There was an increase in the outer intercommisural width in Group 2 compared to group 1 with a significant difference between both groups (P < 0.046). A significant decrease in the upper lip to upper incisal edge relationship in Group 1 and an insignificant decrease in Group 2 (P = 0.03 and P = 0.262, respectively) was detected. A significant decrease in overbite in Group 1and in Group 2 (P = 0.001) with an insignificant difference between both groups (P > 0.05) was also observed. Conclusion: Smile improvement in the mini-implant group was mainly the result of improved smile arc, increase in outer intercommisural width, decrease in upper lip to upper incisal edge relationship, and decrease in overbite. With the use of accentuated compensating archwires, the only significant change was increase in the interlabial gap.