Effect of Diameter on Stability of Mini-Screws Used as Skeletal Anchorage for Maxillary Canine Retraction Using Two Force Magnitudes.

This study investigated the effect of diameter on stability of mini-screws used as skeletal anchorage for maxillary canine retraction utilizing two different force magnitudes. Findings revealed that increasing the diameter of the mini-screws increases their stability. However, utilization of a high retraction force negatively affects stability especially with small diameters mini-screws.

Effects of molar distalization with the fast back appliance.

UNLABELLED: Few studies had investigated the effectiveness of the Fast Back appliance. As a result of that, this study was concerned about evaluating the dental and skeletal effects of the Fast Back appliance used in distalization of maxillary first molars. MATERIALS AND METHODS: The sample was consisted of 14 female patients. However, four of them discontinued the treatment due to different causes. As a result of this, the study was performed on 10 female patients, with their age ranged from 11-13 years. All patients had skeletal Class I, space deficiency in the upper arch less than 8 mm, and non-extraction lower arch. Distalization using the Fast Back appliance was started at the beginning of the treatment and continued until an overcorrected Class I molar relation was achieved. Lateral cephalometric radiographs and dental casts were obtained before and immediately after distalization, and statistical evaluation of the variables measured on them were done. RESULTS: The maxillary first molars were distalized into an overcorrected Class I in a mean duration of 3.8 months. They were distalized significantly according to cephalometric measurements and dental cast measurements (3.4 +/- 0.71 and 3.69 +/- 1.51 mm respectively) (p< .05), with a significant distal tipping about 3.55 degrees +/- 3.95 degrees and a significant increase in intermolar width by 3.55 +/- 2.58 mm (p< .05). However, the vertical positions of the upper first molars were insignificantly changed (p>. 05), and rotations of these teeth were negligible (p>. 05). Loss of anchorage was evidenced by the significant mesial movements of the upper first premolars. They were significantly tipped mesially, rotated, and extruded (p< .05). On the other hand, the interpremolar distance was insignificantly changed. The overjet was significantly increased and the overbite was significantly decreased. The skeletal changes sagitally and vertically were insignificant, except for the increase in mandibular plane angle (FMA angle) which was signficant. CONCLUSIONS: The Fast Back is an efficient noncompliance appliance to distalize molars without rotations. However, these movements are associated with distal molar tipping and anchorage loss of the anterior teeth.

The effect of submucosal injection of platelet-rich fibrin vs. platelet-rich plasma on orthodontic tooth movement in rabbits; 28 days follow-up.

OBJECTIVE: This study aimed to compare between the effects of submucosal injection of platelet rich fibrin (i-PRF) versus platelet rich plasma (PRP) on orthodontic tooth movement (OTM) in a rabbit model over a 28-day follow-up period. MATERIALS AND METHODS: Sixty-three rabbits were assigned into 3 equal groups. Group I animals were subjected to the OTM without any treatments and considered as the control. Whereas groups II and III were handled as group I and instead i-PRF and PRP were injected submucosally in the buccal vestibular mucosa next to the mandibular 1st premolar, respectively. The distance of OTM was consecutively measured clinically after 7, 14 and 28 days. Seven rabbits from each group were euthanized after 7, 14 and 28 days for histological evaluation. Two-way ANOVA followed by LSD post-hoc statistical tests were used for comparison. RESULTS: After 28 days, the mean tooth movements were 4.36±0.04mm in the control group, 6.30±0.06mm in the group receiving PRP and, 6.85±0.09mm in the group receiving i-PRF. Statistical analysis for the values of teeth movements revealed highly significant differences between different groups (P=0.001) and between different time periods (P=0.001). Histological analysis showed that submucosal injection of PRP and i-PRF yielded significant differences in periodontal ligament width in compression and tension sides between different groups (P=0.001) and between different time periods (P=0.001). CONCLUSION: Submucosal injection of either PRP or i-PRF is a minimally invasive and safe approach for accelerating OTM. In this rabbit model, the effect of i-PRF is significantly more pronounced than the effect of PRP.

Effect of early orthodontic force on shear bond strength of orthodontic brackets bonded with different adhesive systems.

INTRODUCTION: This study was conducted to evaluate the effect of applying early orthodontic force on the shear bond strength (SBS) of orthodontic brackets bonded with 4 adhesive systems. METHODS: Eighty stainless steel brackets were bonded to the enamel surfaces of extracted premolars with 4 adhesive systems. For each adhesive, 10 brackets were bonded without application of force (groups 1, 3, 5, and 7), and another 10 were subjected to a 120-g force with a coil spring (groups 2, 4, 6, and 8). This force was applied 30 minutes after bonding and maintained for 24 hours. Groups 1 and 2 had Rely-a-bond primer and Rely-a-bond adhesive (Reliance Orthodontic Products, Itasca, Ill). Groups 3 and 4 had Transbond XT primer and Transbond XT adhesive (3M Unitek, Monrovia, Calif). Groups 5 and 6 had Transbond Plus Self Etching Primer and Transbond XT adhesive (3M Unitek). Groups 7 and 8 had RelyX Unicem (3M ESPE, Seefeld, Germany). After thermocycling, SBS testing was performed by using a universal testing machine (Type 500, Lloyd Instruments Ltd, Fareham Hants, UK). The results of SBS testing for all adhesives were analyzed by 2-way analysis of variance and the Duncan test. The unpaired Student t test was used to compare the effect of force on the SBS of each adhesive. RESULTS: Transbond XT primer and its adhesive had the highest values (without force, 11.2 +/- 3.1 MPa; with force, 10.7 +/- 2.7 MPa), and RelyX Unicem had the lowest (without force, 5.8 +/- 1.5MPa; with force, 5.7 +/- 1.6 MPa). Application of force yielded nonsignificant reductions in SBS for all adhesives; this reduction was less pronounced with RelyX Unicem. CONCLUSIONS: For all studied adhesive systems, orthodontic force up to 120 g can be applied within the first hour after bonding with no deleterious effects on bond strength.

Characteristics of adhesive bonding with enamel deproteinization.

OBJECTIVE: To evaluate the effect of using sodium hypochlorite (NaOCl) on the bond characteristics of orthodontic metal brackets bonded to enamel surface using three adhesive systems. METHODS: One hundred twenty premolars were selected and randomly divided into two equal groups of 60 teeth/ each (Groups I and II). The teeth of Group I were left untreated while those of Group II were exposed to 5.25% NaOCl for 1 minute. The teeth in either group were randomly subdivided into three equal subgroups of 20 teeth/ each (A, B and C), according to the type of adhesive system used to bond the brackets. In Subgroup A, phosphoric acid + Transbond XT primer and adhesive were used. In subgroup B, Transbond Plus self-etching primer (SEP) + Transbond XT adhesive were utilized. In subgroup C, phosphoric acid + SmartBond LC adhesive were used. The shear bond strength (SBS) and the degree of adhesive penetration to enamel surface were assessed. Data analyses were performed using ANOVA, post-hoc (LSD), t and chi-square test. RESULTS: Transbond XT had significantly higher SBS than SmartBond LC (p< 0.05). Phosphoric acid provided significantly higher SBS and degree of adhesive penetration than SEP (p< 0.05). NaOCl significantly increased SBS and degree of adhesive penetration in Subgroups B and C (p< 0.05). CONCLUSION: Adhesion quality of Transbond XT adhesive is better than SmartBond LC. Phosphoric acid is more effective than SEP. NaOCl enhances the bond characteristics.

Decalcification prevention around orthodontic brackets bonded to bleached enamel using different topical agents.

BACKGROUND: The present study was conducted to evaluate the effect of different topical agents utilized for prevention of enamel decalcification around orthodontic brackets bonded to bleached and non-bleached enamel. METHODS: Human maxillary premolars (n = 120) were divided into two equal groups. Teeth in group I were left without bleaching while those in group II were bleached with Vivastyle gel. Metal brackets were bonded to all the teeth using light-cured adhesive. Each group was divided into six equal subgroups (A, B, C, D, E, and F). In subgroup A, no material was applied (control). In subgroups B, C, D, E, and F, the following materials were applied respectively: Profluorid varnish, Enamel Pro Varnish, Ortho-Choice Ortho-Coat, GC Tooth Mousse, and GC MI Paste Plus. All teeth were cycled in a demineralization solution/artificial saliva for 15 days. Laser fluorescence was used to measure the level of enamel mineralization. The data were statistically analyzed. RESULTS: Regarding the non-bleaching subgroups, all studied material revealed significant demineralization reduction in comparison to the control subgroup (P < 0.05). Ortho-Choice Ortho-Coat revealed the highest significant effect while GC Tooth Mousse showed the least effect. In bleached subgroups, Profluorid varnish, Enamel Pro Varnish, and Ortho-Choice Ortho-Coat significantly reduced demineralization (P < 0.05) while either GC MI Paste Plus or GC Tooth Mousse had no significant effects (P > 0.05). CONCLUSIONS: Ortho-Choice Ortho-Coat, and Profluorid and Enamel Pro varnishes could be utilized successfully to reduce enamel demineralization around brackets bonded to either bleached or non-bleached enamel. GC MI Paste Plus and GC Tooth Mousse were effective only in non-bleached enamel.

Characteristics of adhesive bonding with enamel deproteinization

ABSTRACT Objective: To evaluate the effect of using sodium hypochlorite (NaOCl) on the bond characteristics of orthodontic metal brackets bonded to enamel surface using three adhesive systems. Methods: One hundred twenty premolars were selected and randomly divided into two equal groups of 60 teeth/ each (Groups I and II). The teeth of Group I were left untreated while those of Group II were exposed to 5.25% NaOCl for 1 minute. The teeth in either group were randomly subdivided into three equal subgroups of 20 teeth/ each (A, B and C), according to the type of adhesive system used to bond the brackets. In Subgroup A, phosphoric acid + Transbond XT primer and adhesive were used. In subgroup B, Transbond Plus self-etching primer (SEP) + Transbond XT adhesive were utilized. In subgroup C, phosphoric acid + SmartBond LC adhesive were used. The shear bond strength (SBS) and the degree of adhesive penetration to enamel surface were assessed. Data analyses were performed using ANOVA, post-hoc (LSD), t and chi-square test. Results: Transbond XT had significantly higher SBS than SmartBond LC (p< 0.05). Phosphoric acid provided significantly higher SBS and degree of adhesive penetration than SEP (p< 0.05). NaOCl significantly increased SBS and degree of adhesive penetration in Subgroups B and C (p< 0.05). Conclusion: Adhesion quality of Transbond XT adhesive is better than SmartBond LC. Phosphoric acid is more effective than SEP. NaOCl enhances the bond characteristics.

RESUMO Objetivo: avaliar os efeitos do uso de hipoclorito de sódio (NaOCl) sobre as características de colagem de braquetes ortodônticos metálicos na superfície do esmalte, utilizando três sistemas adesivos. Métodos: cento e vinte pré-molares foram selecionados e divididos aleatoriamente em dois grupos iguais, cada um com 60 dentes (Grupos I e II). Os dentes do Grupo I não foram tratados, enquanto os do Grupo II foram expostos ao NaOCl a 5,25% por 1 minuto. Os dentes de ambos os grupos foram subdivididos, aleatoriamente, em três subgrupos iguais, cada um com 20 dentes (A, B e C), de acordo com o tipo de sistema adesivo utilizado para colar os braquetes. No Subgrupo A, foi utilizada a combinação ácido fosfórico + Transbond XT (primer e adesivo). No Subgrupo B, foi utilizada a combinação Transbond Plus autocondicionante (SEP) + Transbond XT (adesivo). No Subgrupo C, foi utilizada a combinação ácido fosfórico + SmartBond LC (adesivo). Foram avaliados a resistência ao cisalhamento e o grau de penetração do adesivo na superfície do esmalte. A análise dos dados foi realizada utilizando-se os testes ANOVA, post-hoc (LSD), t e qui-quadrado. Resultados: o Transbond XT teve uma força de adesão significativamente maior do que o SmartBond LC (p< 0,05). O ácido fosfórico propiciou força de adesão e grau de penetração do adesivo significativamente maiores do que o SEP (p< 0,05). O NaOCl aumentou significativamente a força de adesão e o grau de penetração do adesivo nos Subgrupos B e C (p< 0,05). Conclusão: a qualidade da adesão do adesivo Transbond XT é melhor que a do SmartBond LC. O ácido fosfórico é mais eficiente do que o SEP. O NaOCl melhora as características da colagem.