Effect of CO2 laser (10.6 µm) and Remin Pro on microhardness of enamel white spot lesions.

This study investigated the combined effect of CO2 laser irradiation and Remin Pro paste on microhardness of enamel white spot lesions (WSLs). Seventy-eight intact premolars were randomly assigned into six groups and then stored in a demineralizing solution to create WSLs. Afterwards, the teeth in group 6 (negative control) remained untreated, while groups 1 and 4 were exposed to CO2 laser irradiation (20 Hz, 1 W, 30 s) and Remin Pro paste, respectively. In groups 2 and 3, the teeth were exposed to laser either before (group 2) or after (group 3) Remin Pro application. The teeth in groups 1 to 5 were then immersed in artificial saliva for 90 days while subjected to fluoride mouthwash and weekly brushing. Finally, the teeth were sectioned, and Vickers microhardness was measured at the enamel surface and at 50, 100, and 150 µm from the surface. One sample of each group was also examined with scanning electron microscope (SEM). Data were analyzed by two-way analysis of variance (ANOVA) and Tukey's test. The significance was set at 0.05. Laser irradiation followed by Remin Pro application (group 2) caused a significant increase in total WSLs' microhardness compared with laser alone (group 1) and control groups (P < 0.05). Microhardness at depths of 100 and 150 µm was also significantly greater in group 2 compared with those of group 3 and control groups (P < 0.05). Combined application of CO2 laser with Remin Pro paste, when laser is irradiated before the paste, is suggested for re-hardening of WSLs in deep layers of enamel.

Effects of Diode Laser Debonding of Ceramic Brackets on Enamel Surface and Pulpal Temperature.

AIM: Debonding of ceramic brackets due to their high bond strength and low fracture toughness is one of the most challenging complications of orthodontic clinicians. Application of lasers might be effective in the debonding of ceramic brackets as they reduce bond strength of resins and, therefore, can eliminate the risk of enamel damage. However, the thermal effects of laser radiation on dental tissue can cause undesirable results. The aim of this study is to evaluate the enamel surface characteristics and pulpal temperature changes of teeth after debonding of ceramic brackets with or without laser light. MATERIALS AND METHODS: Thirty polycrystalline brackets were bonded to 30 intact extracted premolars, and later debonded conventionally or through a diode laser (2.5 W, 980 nm). The laser was applied for 10 seconds with sweeping movement. After debonding, the adhesive remnant index (ARI), the lengths and frequency of enamel cracks were compared among the groups. The increase in intrapulpal temperature was also measured. The collected data were analyzed by Chi-squared test and paired t-test using Statistical Package for Social Sciences (SPSS) software. RESULTS: There was no case of enamel fracture in none of the groups. Laser debonding caused a significant decrease in the frequency and lengths of enamel cracks, compared to conventional debonding. In laser debonding group, the increase in intrapulpal temperature (1.46°C) was significantly below the benchmark of 5.5°C for all the specimens. No significant difference was observed in ARI scores among the groups. CONCLUSION: Laser-assisted debonding of ceramic brackets could reduce the risk of enamel damage, without causing thermal damage to the pulp. However, some increases in the length and frequency of enamel cracks should be expected with all debonding methods.

Effect of Erbium:YAG Laser Recycling on Mechanical Characteristics of Retrieved Orthodontic Mini-screws.

Introduction: This study aimed to evaluate the influence of two recycling methods on the mechanical and surface characteristics of orthodontic mini-screws. Methods: Thirty-six retrieved mini-screws were randomly classified into two equal groups. In the first group (laser recycled group (LG)), the Er:YAG laser (2940 nm, 5.5 W, 275 mJ, perpendicular to the mini-screws at a distance of 7-10 mm, 25 s) was used to recycle mini-screws. In the second group (phosphoric acid and sodium hypochlorite recycled group (ASG)), the mini-screws were kept in 37% phosphoric acid gel (10 minutes) and then placed in 5.25% sodium hypochlorite for 30 minutes. Eighteen new mini-screws were selected as the control group (CG). Maximum insertion torque (MIT), maximum removal torque (MRT), and fracture torque (FT) of all mini-screws were measured. A sample from each group was examined for the surface changes of the mini-screw and tissue remnants under a scanning electron microscope (SEM). Results: The mean MIT was significantly higher in both LG and ASG groups than the CG (P<0.001 and P=0.002, respectively). However, no significant difference was shown between the LG and ASG groups. The mean values of MRT and FT showed no significant difference between the groups. The amount of tissue remnants in the ASG group was significantly higher than that in the LG group. The evidence of porosity and corrosion was observed on the ASG mini-screw surface, and there was an increase in roughness on the LG mini-screw surface. Conclusion: The Er:YAG laser recycling of mini-screws is a proper method causing minimum damage to the screw surface.

Effect of Low-Level Laser Therapy on Patients With Class II Mandibular Deficiency Treated with Farmand Functional Appliance.

Introduction: Considering the positive effects of a low-level laser on new bone formation, we aimed to investigate the effects of a low-level laser in the treatment of patients with class II mandibular deficiency treated with Farmand functional appliance. Methods: Twenty-two growing patients aged 10-14 years were randomly divided into "Farmand" and "Farmand+Laser" groups. All patients were treated with Farmand functional appliance. Patients in the "Farmand+laser" group were exposed to laser irradiation (980 nm, 100 mw, 4 points around temporomandibular joints, 100 seconds each point) weekly for three months after 3-4 weeks of using the appliance. Lateral cephalometry radiographs were taken from all patients before and after the treatment period, and changes in skeletal and dental parameters were measured. Results: The association of the particular laser irradiation with the functional appliance led to a greater increase in the effective length of the mandible (Co-Gn, P=0.048), the anterior sagittal position of the mandible (SNB, P=0.029), and the length of the ramus (Co-Go, P=0.028), and it showed a further decrease in the discrepancy between the jaws (ANB, P=0.000) compared with the functional appliance alone. Conclusion: The application of the laser with the chosen parameters and protocol in conjunction with the functional appliance improved the effects of the functional appliance and reduced the discrepancy between the two jaws.

Comparative evaluation of three methods of adhesive remnant removal after orthodontic bracket debonding.

OBJECTIVE: This study aimed to assess the effects of three methods of adhesive remnant removal (carbide bur and low speed handpiece, carbide bur and high speed handpiece, and zircon-rich glass fiber reinforced composite bur), after orthodontic bracket debonding, on tooth color and enamel surface roughness. METHODS: Ninety sound premolar teeth were selected. The baseline tooth color was assessed using Vita spectrophotometer. The teeth were subjected to bracket bonding processes and then randomly divided into three equal groups. In each group, composite remnant was removed by one of the three methods of adhesive removal, and the teeth were then subjected to color assessment again. To measure the surface roughness, a scanning electron microscope (SEM) with x400 magnification was used. RESULTS: ANOVA showed that the effect of the three methods of adhesive remnant removal on ∆L, ∆b and ∆E was statistically significant (p=0.01), but without significant effect on ∆a. Comparison of the means showed that composite bur and high speed carbide bur yielded the highest ∆E (p=0.05), and had a significant difference when compared to carbide bur and low speed handpiece. The highest ∆L and ∆b values belonged to samples approached with composite bur and carbide bur with high speed handpiece, respectively. SEM analysis showed that the composite bur created a very smooth surface, compared to the other two methods. CONCLUSION: Zircon-rich glass fiber reinforced composite created the smoothest enamel surface and highest color change, when compared to the other two methods.

Diode Laser Irradiation Effects on Miniscrew Stability and IL-1ß and TGF-ß1 Levels: A Split-Mouth Randomized Controlled Clinical Trial.

Introduction: This study aimed to assess the effect of low-level laser therapy (LLLT) on miniscrew stability and concentrations of interleukin-1ß (IL-1ß) and transforming growth factor-beta (TGF-ß1) in peri-miniscrew crevicular fluid in the course of orthodontic treatment. Methods: This randomized split-mouth double-blind clinical trial evaluated 18 patients requiring anterior retraction along with maximum anchorage. Miniscrews were placed between the maxillary second premolar and first molar. A diode laser was irradiated with a 980-nm wavelength and 100-mW output power in continuous-wave mode at four time points: T0 (1 hour after miniscrew placement), T1 (1 week later), T2 (at 1 month) and T3 (at 3 months) in one quadrant of the maxilla (laser group). The other quadrant of the maxilla underwent the pseudo-application of the laser (control group). The primary stability of miniscrews was measured by Periotest M and reported as Periotest value (PTV). Also, at each time point, samples were collected from the peri-miniscrew crevicular fluid one hour after laser irradiation to assess the concentration of IL-1ß and TGF-ß1. Results: The mean PTV (inverse of the stability) was smaller in the laser group compared with the control group at all time points; this difference was significant at T2 and T3. The mean concentration of IL-1ß in the laser group was lower than that in the control group at all time points, and this difference was significantly remarkable at T0 and T3. The mean concentration of TGF-ß1 in the laser group was lower than that in the control group at T0, T1 and T3; however, the difference was not statistically significant. Conclusion: The current results supported the efficacy of LLLT in increasing the miniscrew stability and decreasing the level of IL-1ß pro-inflammatory cytokine.

In vitro evaluation of microleakage under ceramic and metal brackets bonded with LED and plasma arc curing.

AIM: The aim of the present study was to evaluate these two high intensity light curing units regarding microleakage beneath metal and ceramic brackets. MATERIALS AND METHODS: A total of 60 freshly extracted human premolar teeth were randomly divided into four groups of 15 samples; group I: Metal bracket + LED cured, group II: Ceramic bracket + LED cured, group III: Metal bracket + plasma arc cured, group IV: Ceramic bracket + plasma arc cured. After photopolymerization, the teeth were immersed in water and thermocycled (500 cycles between 5 and 55). Specimens were further sealed with nail varnish and stained with 5% basic fuchsin for 24 hours. All of the teeth were sectioned with two parallel longitudinal occlusogingival cuts and examined under a stereomicroscope. The microleakage was measured with a digital caliper and scored from 0 to 3 for marginal microleakage at the bracket-adhesive and adhesive-enamel interfaces from both the occlusal and gingival margins. RESULTS: Microleakage was detected in all groups. The plasma arc cured group showed less microleakage than light emitting diode (LED) cured in all samples at the enamel-adhesive interface at the gingival margin (ceramic brackets, p = 0.009 and metal brackets, p = 0.005). The plasma arc cured samples showed less microleakage than LED cured in metal brackets at the adhesive-brackets interface at the occlusal margin (p = 0.033). While curing with an LED unit, ceramic brackets displayed significantly less microleakage than metal ones at the gingival margin of adhesive-enamel interface (p = 0.013). The gingival margin in all groups exhibited higher microleakage compared with those observed in occlusal sides in all sample groups (p < 0.001). CONCLUSION: 1. LED units cause more microleakage than plasma arc units. 2. In all groups the microleakage at the gingival margin is greater than the occlusal margin. CLINICAL SIGNIFICANCE: The microleakage formation permits the passage of bacteria and oral fluids initiating white spot lesions beneath the bracket base.

Stability of pharyngeal airway dimensions: tongue and hyoid changes after treatment with a functional appliance.

UNLABELLED: Because stability is known as the fundamental key of the successful outcome of orthodontics treatment, this study investigated the stability of tongue, hyoid bone and airway dimensions at least two years after active treatment with Faramand functional appliance in patients with class II div 1 malocclusion. CONCLUSION: The present findings indicate that treatment with functional appliance has the potential to increase pharyngeal airway dimensions and changes in tongue and hyoid position. Importantly, these achieved changes seemed to be maintained in long-term, up to 4 years on average.

Evaluation of maxillary arch width and palatal volume and depth in patients with maxillary impacted canine by CBCT.

Introduction: Canines are the second most common tooth in terms of impaction. Impacted teeth can be associated with some different indices of dental arch and dentoalveolar structures. The aim of this study was to evaluate maxillary arch width as well as volume and depth of palate in patients with maxillary impacted canine by cone beam computed tomography (CBCT). Methods: In this cross-sectional study, 45 CBCT images of patients with unilateral maxillary impacted canines were examined. All patients had palatally impacted canines. Three parameters of maxillary arch width, palatal volume and palatal depth were assessed using axial and sagittal incisions on the CBCT images. Then all the measurements on the impacted side were compared with the non-impacted side. Data were entered into SPSS software and paired sample t-test and Student's t-test were used to comparison. The significance level of 0.05 was considered. Results: The maxillary arch width on the impacted side was significantly less than the normal side (P < 0.001). The mean depth of the palate was 14.86 ± 3.53 mm. There was a significant correlation between canine impaction and Palatal volume (R = 0.728 and P-value< 0.001), but no significant correlation between canine impaction and Maxillary arch width was shown (R = 0.15 and p-value = 0.326). Conclusion: The impacted canine was significantly associated with a reduction in the width of the maxillary arch on the affected side, and it made no difference if the impacted side was left or right. Also, impacted canine teeth were significantly associated with volume reduction on the affected side.

A rare case of bilateral double incisors; Early orthodontic management.

A safe and suitable approach in the treatment of unusual malformed anterior maxillary teeth would be to accept a birooted fused incisor as two central teeth by moving it across the midpalatal suture and improve the frontal esthetics.

The Effect of the Er:YAG Laser and MI Paste Plus on the Treatment of White Spot Lesions.

Introduction: White spot lesions (WSLs) occurring after orthodontic treatment lead to patient dissatisfaction and aesthetic problems. The role of calcium-phosphate demineralization systems and the Er:YAG laser in the treatment of these lesions has recently been taken into account. This study aimed to investigate the effect of the Er:YAG laser and MI Paste Plus on the treatment of WSLs. Methods: A total of 65 premolars extracted due to orthodontic treatment were studied in this research. To create enamel lesions, the teeth were placed in a demineralizing solution. The teeth were then randomly divided into five groups (n=13) as follows: first group, control; second group, saliva; third group, MI Paste Plus; fourth group, Er:YAG laser; and fifth group, MI Paste Plus together with the Er:YAG laser. The teeth were kept in artificial saliva between treatment processes. Artificial saliva was replaced daily with fresh artificial saliva. The teeth were sectioned longitudinally by a disc from the middle of the exposed enamel and each section was mounted in polyester resin. The surface of the samples was serially polished and the microhardness of the teeth was measured at depths of 0, 50, 100, and 150 µm. Results: The microhardness was significantly higher in the fifth group than other groups at depths of 50 and 150 µm (P <0.005). Using the laser or MI Paste Plus alone did not significantly increase the microhardness. Conclusions: The combined application of the Er:YAG laser and MI Paste Plus is effective in the treatment of WSLs.

Comparison of antibacterial effects of orthodontic composites containing different nanoparticles on Streptococcus mutans at different times.

INTRODUCTION: Plaque accumulation can cause white spot lesions. Adding nanoparticles to composites can be effective in reducing the number and function of microorganisms. OBJECTIVE: The aim of this study was to evaluate the antibacterial effects of orthodontic composites containing different nanoparticles on Streptococcus mutans at different times. METHODS: Hydroxyapatite, titanium oxides, zinc oxide, copper oxide and silver oxide nanoparticles were prepared at 0.5% and 1% weight concentrations. Accordingly, ten study groups and one control group were obtained. Then, 26 composite discs were prepared from each group. Strain of Streptococcus mutans was cultured, and colonies of Streptococcus mutans were counted. Further bacterial culture was swapped onto enriched Mueller-Hinton agar. The composites were placed on the culture medium, and after incubation the diameter of growth inhibition was measured. To investigate the long-term effect of nanoparticles, the colonies were counted at days 3, 15 and 30. RESULTS: The results showed that 1% copper oxide and 1% silver oxide significantly reduced the number of bacteria (p< 0.05), but there was no significant difference between the other groups and control group (p> 0.05). At day three, there was a significant difference between control group and 0.5% silver oxide, 1% silver oxide and 1% copper oxide groups (p< 0.05). However, colonies had grown in all groups at day 30 but showed no significant difference with control group (p> 0.05). CONCLUSION: Addition of 1% copper oxide and 1% silver oxide has short-term antibacterial effects, so the clinical use of these nanoparticles cannot be justified.

Different modes of diode laser irradiation: effects on enamel surface and intrapulpal temperature at debonding.

BACKGROUND: laser aided debonding of ceramic brackets has been proved to be effective in reducing enamel surface damages, though the optimal parameters of laser to be chose is in question. The aim of this study was to investigate the six different regimens of diode laser irradiation on enamel surface characteristics and intrapulpal temperature changes while debonding. MATERIALS AND METHODS: 90 polycrystalline brackets were bonded to 90 intact extracted premolars. At debonding, teeth were divided into 6 groups (n = 15) and were subjected to the following regimen of diode laser irradiation; G1 = 2 W, continuous wave, G2 = 2.5 W, continuous wave, G3 = 3 W, continuous wave, G4 = 2 W, pulsed mode, G5 = 2.5 W, pulsed mode, G6 = 3 W, pulsed mode. After debonding, the adhesive remnant index, the lengths and frequency of enamel cracks were compared among the groups. 5 teeth out of 15 were randomly selected from each group to assess the intrapulpal temperature changes. RESULTS: The number of enamel cracks increased significantly in all the specimens after debonding. Enamel crack length increased significantly in all the study groups except G3 and G6. The increase in intrapulpal temperature was significantly below the benchmark of 5.5 C for all the specimens. Significant difference was observed in adhesive remnant index scores among the groups and more than half of the teeth showed a score of 2. CONCLUSION: Diode-laser irradiation in pulsed mode or continuous wave at given outputs (2, 2.5, 3 W) were not statistically different in regard to producing enamel surface damages or increasing intrapulpal temperature.

Cephalometric association of mandibular size/length to the surface area and dimensions of the frontal and maxillary sinuses.

OBJECTIVE: This study aimed to determine the cephalometric association of mandibular size/length to the surface area and dimensions of the frontal and maxillary sinuses. MATERIALS AND METHODS: This descriptive study was conducted on 116 digital lateral cephalograms of 38 patients with skeletal Class I malocclusion (normal), 40 patients with skeletal Class II malocclusion with mandibular deficiency, and 38 patients with skeletal Class III malocclusion with mandibular excess. Both male and female patients were included. Using AutoCAD 2016 software, the anteroposterior dimension, height and surface area of the frontal and maxillary sinuses, mandibular body length and cephalometric indices including anterior and posterior cranial bases, and growth pattern indices were measured on lateral cephalograms. RESULTS: Dimensions and surface area of the frontal and maxillary sinuses in skeletal Class III malocclusion were greater than those in other groups. These variables were significantly correlated with the mandibular body length. The coefficient for the correlation of height, width, and surface area of the frontal sinus with mandibular body length was 0.253, 0.284, and 0.490, respectively. The coefficient for the correlation of height, length, and surface area of the maxillary sinus with mandibular body length was 0.346, 0.657, and 0.661, respectively. These variables (except for the frontal sinus width) had a significant correlation with the anterior and posterior cranial bases. The frontal sinus width had a significant correlation with the anterior cranial base. These variables in males were greater than those in females. CONCLUSION: The dimensions and surface area of the frontal and maxillary sinuses in skeletal Class III malocclusion were greater than those in other groups. These variables (except for the frontal sinus width) had a significant correlation with the anterior and posterior cranial bases and mandibular body length.

Evaluation of the effect of two types of laser on the growth of streptococcus mutans.

BACKGROUND AND AIMS: This study was done to compare the antibacterial effect of Photodynamic therapy (PDT) on streptococcus mutans (S. mutans) using two different light sources and photosensitizers (PS). MATERIALS AND METHODS: Five groups were studied in this research:no light and no toluidine blue ortho (TBO) as PS for control group, irradiation only (CO2 laser or Nd:YAG laser), and irradiation with PS (CO2 laser and TBO or Nd:YAG laser and TBO). Standard suspensions of S. mutans, based on the type of group, were used in different PDTs. Bacterial suspension from each treatment was subcultured onto the surface of Mueller-Hinton agar plates, and bacterial growth was assessed. The results were analyzed by analysis of variance (ANOVA). RESULTS: There was a statistically significant reduction in the viability of S. mutans in TBO with CO2 laser and TBO with Nd:YAG laser groups (p value < 0.05). However, there was no significant difference between control and groups treated with lasers only. The highest number of the colonies of S. mutans in treated groups was observed in CO2 laser irradiation only and the lowest number was seen in CO2 laser with TBO. In the groups irradiated alone (without TBO), no significant reduction of colonies was observed. There was no significant difference between the experimental groups. CONCLUSIONS: The colonies of S. mutans were susceptible to either CO2 laser or Nd:YAG laser in the presence of TBO with no significant difference. So these lasers with this photosensitizer may be useful in prevention of dental caries and antimicrobial treatment protocols.

Effect of Methylphenidate on Orthodontic Tooth Movement and Histological Features of Bone Tissue in Rats: An Experimental Study.

INTRODUCTION: Methylphenidate is a psychostimulant drug, which is commonly used by children and teenagers. This age group receives most orthodontic treatment. Effect of this drug on tooth movement is unknown. AIM: The aim of this study was to evaluate the effect of methylphenidate on orthodontic tooth movement and histological features of bone tissue in rats. MATERIALS AND METHODS: Forty-two Wistar rats (male) were selected and divided to three groups, randomly (n=14). The control group (Group 1) received no drug, the experimental Group 2 received a constant dose of methylphenidate daily for 14 days while the experimental Group 3 received increasing doses of methylphenidate daily. To exert force, a NiTi coil spring was placed between the maxillary right first molar and the maxillary right central incisor. At the end of the study period, the amount of tooth movement was measured and then the rats were sacrificed for histological analysis of bone tissue. Differences between the experimental groups were analysed using Kruskal-wallis and Mann-Whitney U tests. RESULTS: No significant differences were found in the amount of orthodontic tooth movement or osteoclasts and lacunae, between the experimental groups (p>0.05). Mann-Whitney U analysis showed significant differences in the depth of resorption lacuna between Group 2 and 3 (p=0.037). CONCLUSION: Methylphenidate has no significant effect on orthodontic tooth movement or histological features of bone tissue in rats.

Oral Complications of The Oromaxillofacial Area Radiotherapy

Background: The incidence of malignancies is on the rise in different communities, making them the second most important cause of mortality in developed countries. One of the treatment modalities for these malignancies, apart from surgery and chemotherapy, is radiotherapy which might in itself lead to some complications in the area receiving radiation. The present study was undertaken to evaluate the prevalence of oral complications in patients undergoing radiotherapy of the oromaxillofacial area in Shahid Ramazanzadeh Radiotherapy Center in Shahid Sadoughi University of Medical Sciences. Materials and Methods: The present descriptive/analytical study was carried out from 2014 to 2015 on 144 patients with head and neck malignancies, referring to Shahid Ramazanzadeh Radiotherapy Center, Yazd, Iran. The patients underwent intraoral examinations before radiotherapy, during the second week after radiotherapy and at the end of radiotherapy. The patients' background data and the presence of oral complications were recorded in special forms. Data were analyzed with SPSS 17, using chi-squared test. Results: Of 144 patients evaluated, 51 were male and 93 were female. During the final examination, all the subjects (100%) had mucositis, xerostomia and candidiasis, with 85.4% of the subjects (123 patients) suffering from gustatory disturbances. Although only 38.1% of the subjects had oral ulcers at the end of the second week, all of them (100%) exhibited such lesions in the final examination. The prevalence rate of tooth hypersensitivity at this stage was 22.9%. During the second examination, 117 subjects (83.3%) exhibited grade I trismus, 42 of which exhibited deterioration toward grade II during the final examination. Conclusion: The results of the present study showed a high rate of oral complications in patients undergoing head and neck radiotherapy. Mucositis, xerostomia and candidiasis were the most prevalent complications.

Comparative evaluation of three methods of adhesive remnant removal after orthodontic bracket debonding

ABSTRACT Objective: This study aimed to assess the effects of three methods of adhesive remnant removal (carbide bur and low speed handpiece, carbide bur and high speed handpiece, and zircon-rich glass fiber reinforced composite bur), after orthodontic bracket debonding, on tooth color and enamel surface roughness. Methods: Ninety sound premolar teeth were selected. The baseline tooth color was assessed using Vita spectrophotometer. The teeth were subjected to bracket bonding processes and then randomly divided into three equal groups. In each group, composite remnant was removed by one of the three methods of adhesive removal, and the teeth were then subjected to color assessment again. To measure the surface roughness, a scanning electron microscope (SEM) with x400 magnification was used. Results: ANOVA showed that the effect of the three methods of adhesive remnant removal on ∆L, ∆b and ∆E was statistically significant (p=0.01), but without significant effect on ∆a. Comparison of the means showed that composite bur and high speed carbide bur yielded the highest ∆E (p=0.05), and had a significant difference when compared to carbide bur and low speed handpiece. The highest ∆L and ∆b values belonged to samples approached with composite bur and carbide bur with high speed handpiece, respectively. SEM analysis showed that the composite bur created a very smooth surface, compared to the other two methods. Conclusion: Zircon-rich glass fiber reinforced composite created the smoothest enamel surface and highest color change, when compared to the other two methods.

RESUMO Objetivo: O presente estudo teve como objetivo avaliar os efeitos de três métodos de remoção de adesivo remanescente (broca carbide e peça de mão em baixa rotação, broca carbide e peça de mão em alta rotação, e broca de compósito reforçado com fibra de vidro rica em zircônia), após a descolagem de braquetes ortodônticos, sobre a cor dos dentes e rugosidade superficial do esmalte. Métodos: Noventa pré-molares hígidos foram selecionados. A cor inicial dos dentes foi avaliada usando um espectrofotômetro Vita. Os dentes foram submetidos à etapa de colagem dos braquetes e, então, divididos aleatoriamente em três grupos. Em cada grupo, o adesivo remanescente foi removido usando um dos três métodos de remoção, e os dentes foram novamente submetidos à avaliação de cor. Para medir a rugosidade superficial dos dentes, foi usado um microscópio eletrônico de varredura (MEV) com aumento de 400x. Resultados: A ANOVA mostrou que os três métodos de remoção do adesivo remanescente tiveram efeito estatisticamente significativo (p=0,01) em ∆L, ∆b e ∆E, mas sem efeito significativo em ∆a. A comparação das médias mostrou que a broca de compósito e a broca carbide em alta rotação produziram o maior ∆E (p=0,05) e tiveram uma diferença significativa quando comparadas com a broca carbide e a peça de mão em baixa rotação. Os maiores valores de ∆L e ∆b foram encontrados, respectivamente, nos grupos com broca de compósito e broca carbide usando peça de mão em alta rotação. A análise MEV mostrou que o uso da broca de compósito resultou em uma superfície muito lisa, em comparação com os outros dois métodos. Conclusão: Em comparação aos outros métodos, a broca de compósito reforçado com fibra de vidro rica em zircônia criou a superfície de esmalte mais lisa e resultou em uma maior mudança de cor.

Comparison of the Load-Deflection Characteristics of Aesthetic and Conventional Super Elastic Ni-Ti Orthodontic Arch Wires in Conventional and Metal-Insert Ceramic Brackets.

INTRODUCTION: Coated arch wires and ceramic brackets have been introduced to improve aesthetics during orthodontic treatment. AIM: The aim of this study was to determine the effects of coating on the physical properties of aesthetic orthodontic wires. MATERIAL AND METHODS: Five round wires (0.016 inch) were obtained from each of three brands: conventional uncoated super elastic Nickel Titanium (Ni-Ti) (Rematitian Lite; Dentaurum, Ispringen, Germany), HUBIT (Teflon Coated, Korea), G&H (Epoxy Coated, Greenwood, Indiana, USA) which belonged to maxillary arch. Two types of standard ceramic brackets (conventional and metal-insert type, Ortho Technology, Tampa, Florida, USA) with the slot size of 0.022×0.028 inches were used. A simulation device was fabricated to resemble a model of human dental arch and each of the specimen was tested in three-point bending test. The test was conducted in the buccolingual plane with crosshead speed of 1mm/minute pressure from metal pole. Each sample was loaded until a deflection of 3.0 mm was produced. The mean values of maximum loading force, unloading force and clinical plateau length were recorded. One-way ANOVA and Tukey tests were used at p<0.05. RESULTS: Uncoated Ni-Ti arch wire showed higher mean values of maximum loading and unloading force than that of coated aesthetic wires similar to ceramic brackets while G&H wire and metal-insert ceramic brackets presented the lowest values. The longest clinical plateau length was observed in G&H wires and metal-insert ceramic bracket. CONCLUSION: The coating processes for HUBIT (Teflon Coated, Korea), G&H (Epoxy Coated, Greenwood, Indiana, USA) wires might influence bending behaviour which can cause decrease in loading and unloading force.

Comparison of Microleakage under Rebonded Stainless Steel Orthodontic Brackets Using Two Methods of Adhesive Removal: Sandblast and Laser.

OBJECTIVES: Debonding is a common occurrence in orthodontic treatment and a considerable number of orthodontists prefer to rebond the detached brackets because of economic issues. The aim of this study was to compare the microleakage beneath rebonded stainless steel brackets using two methods of adhesive removal namely sandblast and laser. MATERIALS AND METHODS: Sixty human premolar teeth were randomly divided into three groups. Following bonding the brackets, group 1 served as the control group. Brackets in groups 2 and 3 were debonded, and adhesive removal from the bracket bases was done by means of sandblasting and Er-YAG laser, respectively. After rebonding, teeth in each group were stained with 2% methylene blue for 24 hours, sectioned and examined under a stereomicroscope. Marginal microleakage at the adhesive-enamel and bracket-adhesive interfaces in the occlusal and gingival margins was determined. Statistical analysis was done using the Kruskal-Wallis test. RESULTS: Comparison of the microleakage scores among the three groups revealed no statistically significant difference (P > 0.05). At the enamel-adhesive interface, the gingival margins in all groups showed higher microleakage while in the adhesive-bracket interface, the occlusal margin exhibited greater microleakage. CONCLUSION: Er-YAG laser irradiation and sandblasting for adhesive removal from the debonded brackets yielded clinically acceptable microleakage scores.