Orthodontic composite resin bond strength with conventional light and Power Slot curing.

OBJECTIVES: the purpose of this clinical trial was to compare the clinical performance of a new composite resin using two different kind of light curing systems, one conventional and one turbo boosted in a split-mouth design, by using both systems for direct bonding of orthodontic stainless steel brackets in every patient. MATERIALS AND METHODS: fifty patients, 32 females and 18 males, of which 13 were adults (> 18 years of age) with fixed appliances were followed for a mean period of 12 months (range 6-16 months). The performance of 1200 steel brackets was evaluated: 600 were bonded with a conventional light curing (Kulzer light curing machine), curing every bracket for 20 seconds using Quick Cure Composite resin (Reliance Orthodontics), 600 were bonded with a new curing light machine (Reliance Ortho 2000 curing light with Power slot), curing every bracket for 6 seconds. Brackets were bonded both on permanent and on deciduous teeth, since many of these patients were growing patients. RESULTS: the conventional light curing recorded an overall failure rate (26 brackets - 4,3%) significantly higher (p< 0.0360) than Power Slot light curing (13 brackets -2,3%). There were no statistically significant differences (p>0.07) between the failure rates in the upper and lower arches with either light curing systems and also in between anterior and posterior areas. A significant difference was evident, however, among the failure rate of upper total and lower total (p<0.0463) brackets bonded with both systems and was more evident in upper arches bonded with conventional curing system (p<0.0170). It was evident also a higher failure rate in the upper arch compared to the lower arch bonded with conventional light (p<0.0269). CONCLUSIONS: the Power Slot light curing was more effective. But both bonding systems failed mainly at the enamel-adhesive interface, without causing damage to the enamel.

Upper molar distalization: a critical analysis.

Traditional upper molar distalization techniques require patient co-operation with the headgear or elastics. Recently, several different intraoral procedures have been introduced to minimize the need for patient co-operation. This article reviews the appliances currently available for maxillary molar distalization and critically analyses their dentoalveolar and skeletal effects.

Halogen versus high-intensity light-curing of uncoated and pre-coated brackets: a shear bond strength study.

AIM: To evaluate the shear bond strengths of adhesive pre-coated brackets (APC) and conventional uncoated brackets (Victory) cured with two different light-curing units: a conventional halogen light (Visilux 2) and a micro-xenon light (Aurys). SETTING: Ex vivo study MATERIALS AND METHODS: Sixty freshly extracted bovine permanent mandibular incisors were randomly assigned to one of four groups, each group consisting of 15 specimens. Two groups (one for each type of bracket) were exposed to the halogen light for 20 seconds and used as controls. The remaining two groups were cured with the micro-xenon light for 2 seconds. After 24 hours, all samples were tested in a shear mode on an Instron Machine. Analysis was by two-way ANOVA with Scheffé's test for comparisons, Kaplan-Meier survival estimates, and Cox model. The Chi-square (chi(2)) test was used to determine significant differences in the ARI scores. RESULTS: The mean shear bond strength of the uncoated brackets cured with Visilux 2 was significantly higher than those of all the other groups tested. Both groups cured with Visilux 2 produced significantly higher mean shear bond strengths than those of the corresponding groups cured with Aurys. No statistically significant differences were found between the two groups cured with Aurys. CONCLUSIONS: Compared to halogen light-curing, the micro-xenon light enables the clinician to reduce significantly the curing time of both APC and uncoated brackets, and although significantly lower, their shear bond strengths may be clinically acceptable.

Mesial bodily movement of maxillary and mandibular molars with segmented mechanics.

The displacement of teeth into areas with substantial atrophy of the alveolar ridge or through the maxillary sinus has been considered a major limitation. Bone formation can, however, be generated if the orthodontic appliance can produce the necessary strain distribution along the entire periodontal ligament. The aim of this case report is to illustrate how bone formation can accompany mesial bodily movement of maxillary and mandibular molars. The necessary strain distribution was generated by the rational use of segmented mechanics. The use of superelastic Ni-Ti springs allows the application of low and constant forces over a wide range of deactivation, thus providing a uniform strain in the periodontium. The result of those appliances is highly predictable and side effects can be minimized effectively.

Effects of conventional and high-intensity light-curing on enamel shear bond strength of composite resin and resin-modified glass-ionomer.

The purpose of this study was to evaluate the shear bond strengths of a composite resin (Transbond XT; 3M/Unitek, Monrovia, Calif) and a resin-modified glass ionomer (Fuji Ortho LC; GC America Inc, Alsip, Ill) cured with 2 different light-curing units: a conventional visible light unit (Ortholux XT; 3M Dental Products, St Paul, Minn) and a xenon arc light unit (Plasma Arc Curing [PAC] System; American Dental Technologies, Corpus Christi, Texas). One hundred twenty freshly extracted bovine permanent mandibular incisors were randomly divided into 1 of 8 groups; each group consisted of 15 specimens. Two groups (1 group for each type of adhesive) were exposed to the visible light for 20 seconds (Transbond XT) and 40 seconds (Fuji Ortho LC), respectively, and used as control groups. The remaining 6 groups (3 for each adhesive) were cured with the xenon arc light for 2, 5, and 10 seconds. After bonding, all samples were stored in distilled water at room temperature for 24 hours and subsequently tested in a shear mode on an Instron universal testing machine (Instron Corp, Canton, Mass). For the groups bonded with Transbond XT, no statistically significant differences (P =.868) were found between the shear bond strength of the control group cured with Ortholux XT and those of the groups cured with the PAC System for 2, 5, or 10 seconds. When the shear bond strengths of the groups bonded with Fuji Ortho LC were evaluated, no statistically significant differences (P =.087) were found between the control group that was cured with Ortholux XT and those cured with the PAC System. The bond strength of the composite resin was significantly higher than that of the resin-modified glass ionomer in all the groups tested (P <.0001). The present findings indicate that, compared with visible light-curing, the xenon arc light enables the clinician to significantly reduce the curing time of both bonding agents, without affecting their shear bond strengths. Therefore, xenon arc light sources can be recommended as an advantageous alternative for curing both composite resins and resin-modified glass ionomers.

Growth hormone treatment promotes guided bone regeneration in rat calvarial defects.

This study evaluated the biomechanical strength and bone formation in calvarial critical size bone defects covered with expanded polytetrafluoroethylene (e-PTFE) membranes in rats treated systemically with recombinant human growth hormone (rhGH). A full-thickness bone defect, 5 mm in diameter, was trephined in the central part of each parietal bone in 40 one-year-old female Wistar rats, which were randomly assigned to two groups of 20 animals each. The bone defects were covered with an exocranial and an endocranial e-PTFE membrane. From the day of operation, the rhGH-treated animals were given 2.7 mg rhGH/kg/day and the placebo-injected rats were given isotonic sodium chloride. The animals were killed 28 days after operation. The biomechanical test was performed by a punch out test procedure placing a 3.5-mm diameter steel punch in the centre of the right healed defect. After mechanical testing, the newly formed tissue inside the defect was removed and the dry and ash weights were measured. The left healed defects were used for three-dimensional (3D) reconstruction by means of micro-computer tomography (micro-CT). Ultimate load, ultimate stiffness, and energy absorption at ultimate load were significantly increased in the rhGH-treated group (P < 0.003). Also, tissue dry and ash weights were significantly augmented in the rhGH-treated group (P < 0.001). The 3D reconstruction of newly formed bone showed that there was almost twice as much bone volume present in the rhGH-treated defects compared with the placebo group. The experiment demonstrated that rhGH administration enhances bone deposition and mechanical strength of healing rat calvarial defects, covered with e-PTFE membranes.

Clinical comparison between a resin-reinforced self-cured glass ionomer cement and a composite resin for direct bonding of orthodontic brackets. Part 2: Bonding on dry enamel and on enamel soaked with saliva.

The purposes of this investigation were to compare the clinical performance of a resin-reinforced self-cured glass ionomer cement to a standard composite resin in the direct bonding of orthodontic brackets when bonded onto: a) dry teeth and b) teeth soaked with saliva. The two bonding agents were compared using a split-mouth design. In that, both systems were used for direct bonding of stainless steel brackets in every patient. Thirty-eight consecutive patients with fixed appliances were followed for a period of 12 months. The patients were randomly divided into two groups: group A (11 patients) and group B (27 patients). In group A, the performance of 220 stainless steel brackets was evaluated: 110 brackets were bonded with GC Fuji Ortho glass ionomer cement (GC Industrial Co., Tokyo, Japan) onto dry teeth, and 110 bonded with System 1+ composite resin (Ormco Corp., Glendora, CA). In group B, the performance of 540 stainless steel brackets was evaluated: 270 brackets were bonded with GC Fuji Ortho onto teeth soaked with saliva, and 270 bonded with System 1+. In group A, GC Fuji Ortho recorded an overall failure rate (34.5%) significantly higher (p < 0.05) than System 1+ (9%) when applied onto completely dry teeth. Conversely, in group B, no statistically significant differences (p > 0.05) between the failure rates of the two bonding agents were found when GC Fuji Ortho was used on teeth soaked with saliva. It was concluded, therefore, that GC Fuji Ortho shows clinically acceptable bond strengths when bonded onto moist teeth, but not when used on dry enamel. Both bonding agents failed mostly at the enamel/adhesive interface, without causing any enamel damage.

Shear bond strengths of ceramic brackets bonded with different light-cured glass ionomer cements: an in vitro study.

The purpose of this study was to evaluate the shear bond strengths of four light-cured glass ionomer cements used for direct bonding of ceramic brackets, and to compare the results with a two-paste chemically-cured composite resin. Two commercially available polycrystalline ceramic brackets, with either chemically or mechanically retentive bracket bases, were evaluated. The brackets were bonded to 100 freshly extracted bovine incisors, and, after storage in tap water at room temperature for 24 hours, they were subsequently tested in a shear mode using a universal testing machine. The maximum bond strength and the site of bond failure were recorded. With the mechanically retentive base, Fuji Ortho LC produced the highest bond strength (18.50 MPa), which was not significantly different from the values achieved with Concise (14.88 MPa) (P > 0.1) and Photac Bond (13.86 Mpa) (P = 0.1). The lowest bond strength was provided by locomp A20 (5.23 MPa). With the chemically retentive base, the highest bond strength was measured with Concise (29.27 MPa), which was significantly (P < 0.01) higher than the values for Photac Bond (16.27 MPa) and Fuji Ortho LC (13.48 MPa). Again locomp A20 produced the lowest bond strength (3.21 MPa). Three cements (Dyract Ortho, locomp A20 and Fuji Ortho LC) provided higher shear bond strengths with the mechanical retention system, whereas Concise and Photac Bond gave higher strengths with the silane-treated bracket bases. However, the strengths were statistically significantly different only for locomp A20 (P = 0.001) and Concise (P = 0.001). With the mechanically retentive base, Dyract Ortho and locomp A20 failed at the enamel-adhesive interface, whereas Photac Bond and Concise debonded at the bracket-adhesive interface. Fuji Ortho LC failed at both, the bracket-adhesive (40 per cent) and the adhesive-enamel (60 per cent) interface. With the chemically retentive base, all the adhesives failed at the enamel-adhesive interface. Only one bracket fracture occurred in this study, and no enamel damage was detected.

Effects of saliva and water contamination on the enamel shear bond strength of a light-cured glass ionomer cement.

The purpose of this study was to evaluate the shear bond strengths of Fuji Ortho LC (GC Corp., Tokyo, Japan), a light-cured resin-reinforced glass ionomer, used for direct bonding of stainless steel and ceramic brackets under four different enamel surface conditions: (A) nonconditioned and dry, (B) conditioned with polyacrylic acid and moistened with saliva, (C) conditioned with polyacrylic acid and moistened with water, (D) nonconditioned and wet. Stainless steel lingual buttons and two types of polycrystalline ceramic brackets, with either mechanically or chemically retentive bracket bases, were evaluated. The brackets were bonded to 120 freshly extracted bovine incisors; after storage in tap water at room temperature for 24 hours, they were subsequently tested in a shear mode with a universal testing machine. The maximum bond strength and the site of bond failure were recorded. With stainless steel brackets, subgroup B produced the highest bond strength (23.8 MPa), which was significantly (p < 0.05) higher than all the other enamel conditions tested. With ceramic brackets, the highest bond strengths (20.9 MPa and 25.4 MPa, respectively) were measured with subgroup C. Bond failure analysis revealed that each bracket type failed predominantly at the enamel-adhesive interface, except for Transcend 6000. The results indicate that the shear bond strength of Fuji Ortho LC is significantly enhanced by contaminating the enamel surface with either saliva or water after conditioning, depending on bracket type used. Even water contamination of nonconditioned enamel surfaces does not seem to preclude clinically acceptable bond strengths of both stainless steel and ceramic brackets, allowing, at the same time, a safe debonding without enamel damage.

Clinical comparison between a resin-reinforced self-cured glass ionomer cement and a composite resin for direct bonding of orthodontic brackets Part 1: Wetting with water.

The purpose of this study was to compare the clinical performance of a resin-reinforced self-cured glass ionomer cement to a standard composite resin in a split mouth design, by using both systems for direct bonding of orthodontic stainless steel brackets in every patient. Forty eight patients (34 females and 14 males, of which 29 were adults > 18 years of age) with fixed appliances were followed for a mean period of 10 months (range 4-16 months). The performance of 864 stainless steel brackets was evaluated: 404 brackets were bonded with GC Fuji Ortho glass ionomer cement (GC Industrial, Tokyo, Japan) onto teeth soaked with water, and 460 were bonded with System 1+ composite resin (Ormco, Glendora, CA). System 1+ recorded an overall failure rate (18.2%) significantly higher (p < 0.05) than GC Fuji Ortho (7.9%). There were no statistically significant differences (p > 0.05) between the failure rates in the upper and lower arches with either material. Both in the upper and lower arches, System 1+ exhibited a failure rate significantly higher (p < 0.05) than GC Fuji Ortho. When the bonding performance of the six anterior teeth was compared with first and second premolars, no statistically significant differences were found (p > 0.05) between bonding agents in either arch. System 1+ exhibited a failure rate significantly higher (p < 0.05) than GC Fuji Ortho, both in the anterior and posterior segments. Both bonding agents failed mainly at the enamel-adhesive interface, without causing any damage to the enamel.

Light-cured glass ionomer cement as a bracket adhesive with different types of enamel conditioners.

Eighty bovine incisors were ground on 320-grit silicone carbide paper and cleaned with fluoride-free prophylaxis paste. The enamel surface conditions were: 1. no conditioning; 2. salicylic acid (10%, 10s); 3. benzoic acid (10%, 10s); 4. air polishing with sodium hydrogen carbonate/Prophy-Jet; 5. Prophy-Jet, followed by polyacrylic acid (PAA, 10%, 10 s); 6. PAA, followed by saliva contamination; 7. PAA; 8. phosphoric acid (37%, 10 s). Fuji Ortho II LC (GC) was used as a bracket adhesive in groups 1 t0 7, and in group 8 Concise orthodontic (3M). Stainless steel lingual buttons were placed by hand. Polymerisation with visible light was carried out 20 s from mesial, distal, incisal and gingival. After 24 h storage in tap water at room temperature the shear bond strengths were tested in accordance with ISO specification TC 106/SC/WG16. Mean values of the groups were compared using Student's t-test. Group 7 (PAA) attained the highest mean shear strength (in comparison with control group): 28 MPa. This was both significantly different from the control group (Concise, 33 MPa) and highly significant in comparison with the other groups (< 16 MPa). The shear bond strength of Fuji Ortho II LC on PAA conditioned enamel indicates the clinical applicability of this material.

Recycling effects on ceramic brackets: a dimensional, weight and shear bond strength analysis.

The present study investigated the effects of a recycling technique on orthodontic ceramic brackets by means of a scanning electron microscope analysis. The weight and dimension changes of brackets recycled one, five and ten times compared with new ones were evaluated. The results suggest that changes in weight (+4.27 mg), in buccal and base slot widths (-0.0013 inches), in slot depth (+0.0014 inches) and in the total bracket base area (+1.46 mm2) are of little clinical relevance. The shear bond strengths of recycled versus new ceramic brackets were then evaluated and compared. The mean values for new ceramic brackets and brackets recycled one, five and ten times were 15.52, 11.23, 10.10 and 10.04 MPa, respectively, indicating that recycled ceramic brackets provide shear bond strengths adequate for clinical use. Moreover, they exhibit bond failures mostly at the bracket/adhesive interface, without causing enamel damage.