Performance of two laser motion modes versus conventional orthodontic ceramic brackets debonding technique on enamel surface topography.

The risk of enamel deterioration that frequently coexists with debonding of orthodontic teeth brackets elevates the mandate for finding an optimum approach for debonding them without harmful effects. This in-vitro study is intended to compare the effects of two different laser modes (scanning and circular) and a conventional method on the enamel surface after debonding orthodontic brackets. 66 extracted premolars were assigned into 3 groups. After that, light-cure composite resin was used to attach the ceramic brackets to the teeth. Amongst the test groups, Group I: specimens that were debonded using conventional debonding using pliers; Group 2: specimens that were debonded using Er, Cr: YSGG laser applications using the circular motion method; and Group 3: specimens that were debonded using Er, Cr: YSGG laser applications using the scanning motion method. Adhesive Remnant Index (ARI) assessment, intra-pulpal temperature increase, enamel surface roughness after polishing, and assessment of the microstructure of enamel were carried out with scanning electron microscopy. The gathered information was examined statistically. The conventional debonding method had a significantly higher proportion of adhesive remnant index (ARI) scores of 2 and 3 in comparison to the circular (p < .004) and scanning laser groups (p < .001). There was no significant difference in ARI scores between the circular and scanning laser groups (p > .05). Moreover, the circular and scanning laser debonding methods resulted in a significantly higher proportion of Enamel Surface Roughness (ESR) scores of 0 and a lower proportion of ESR scores of 3 compared to the conventional technique group (p < .001). However, there was no significant difference in ESR scores between the circular and scanning laser methods (p = .945). Lastly, the average intra-pulpal temperature was significantly higher in the circular laser group (1.9 ± 0.5 ) compared to the scanning laser group (0.9 ± 0.2) with p < .001. Er, Cr: YSGG laser irradiation is a tool that shows promise for debonding ceramic brackets with minimal harm to the enamel surface. The scanning laser technique is more desirable due to the lower intra-pulpal temperature increase.

Effects of the conventional, soft start, and pulse delay modes produced by light-emitting diode device on metal brackets bond strength and enamel damage: An in vitro comparative study.

OBJECTIVES: This study aimed to compare the bond strength and enamel damage following debonding of metal brackets cured by different light-curing modes: conventional, soft start, and pulse delay modes. MATERIAL AND METHODS: Sixty extracted upper premolars were randomly divided into three groups according to the used light-curing mode. Metal brackets were bonded with a light-emitting diode device employing different modes. Group 1: conventional mode (10s mesial+10 s distal); group 2: soft start mode (15s mesial+15s distal); group 3: pulse delay mode (3s mesial+3s distal, followed by 3min of no photoactivation, then 9s mesial+9s distal). Radiant exposure was the same in all study groups. Shear bond strengths of the brackets were tested with a universal testing machine. A stereomicroscope was used to determine the number and length of enamel microcracks. One-Way ANOVA and Kruskal-Wallis tests were used to detect significant differences in shear bond strength and microcracks number and length among groups. RESULTS: The soft start and pulse delay modes produced significantly greater shear bond strength than the conventional mode (19.46±4.90MPa; 20.47±4.97MPa; 12.14±3.79MPa, respectively, P<0.001). However, there was no significant difference between the soft start and pulse delay groups (P=0.768). The number and length of microcracks increased significantly after debonding in all study groups. The change in microcracks length was not different among study groups. CONCLUSION: The soft start and pulse delay modes produced greater bond strength than the conventional mode without predisposing enamel to higher risk of damage. Conservative methods for debonding are still required.

Thermal effect of Er:YAG and Er,Cr:YSGG used for debonding ceramic and metal orthodontic brackets: An experimental analysis.

BACKGROUND: In orthodontics, erbium (Er:YAG) lasers can be used for bracket debonding. OBJECTIVES: To assess the changes in temperature of pulp and enamel during laser debonding of brackets. MATERIAL AND METHODS: A total of 13 brackets (n = 13; 2 metal and 11 ceramic brackets) were bonded to 13 caries-free premolars extracted for orthodontic reasons. Brackets were irradiated with 2 lasers. Laser No. 1 was an erbium-chromium (Er,Cr:YSGG) laser (Waterlase Express; Biolase, Irvine, USA) with a wavelength of 2,780 nm at a power of 2.78-2.85 W, energy of 185-190 mJ, fluence of 10 ns, frequency of 25 Hz, pulse duration of 300 µs, tip diameter of 0.6 mm, air/fluid cooling of 3.5 mL/s, and time of irradiation of 5-25 s. Laser No. 2 was an Er:YAG laser (LiteTouch; Light Instruments Ltd., Yokneam, Israel) with a wavelength of 2,940 nm at a power of 4 W, energy of 200 mJ, fluence of 10 ns, frequency of 20 Hz, pulse duration of 300 µs, tip diameter of 0.8 mm, air/fluid cooling of 3.5 mL/s, and time of irradiation of 5-15 s. Two thermographic cameras (FLIR Zenmuse XT and FLIR P65; FLIR Systems, Wilsonville, USA) and type K thermocouple (Zhangzhou Weihua Electronic Co., Fujian, China) were used for precise temperature measurement on the surface of the teeth and inside them. RESULTS: When laser No. 1 was in use, the mean difference between the inner and outer temperature of the examined teeth (1.4°C) was higher than when the laser No. 2 was in use (0.6°C) (p = 0.0974). The study found that the temperature inside the tooth did not increase, and it even decreased during treatment with Er:YAG laser using water cooling, provided that appropriate proportion of water and air was used. For laser No. 1, confidence interval (CI) was between 0.7 and 2.2 and for laser No. 2 it was between 0.500 and 1.23. Only experiment for ceramic brackets was described. CONCLUSIONS: These findings confirm that the use of Er:YAG family lasers for orthodontic bracket debonding in an in vitro study is safe and effective.

¿Es el descementado, un paso clínico crítico? / The clinical procedure of debonding

El procedimiento clínico de descementado de brackets es crítico para el esmalte. La superficie dentaria queda dañada después de este paso clínico, que, en un principio, parecería sencillo e inocuo. El propósito de este trabajo fue examinar la superficie del esmalte luego del descementado y pulido final. Para tal fin se utilizó la magnificación de imágenes, mediante el empleo de un microscopio óptico de luz coaxial. La muestra incluyó el análisis de 10 arcadas superiores de pacientes en la etapa final de tratamiento.

The clinical procedure of debonding of brackets is critical for the enamel. The dental surface remains damaged after this clinical step, which in principle would seem simple and harmless. The purpose of this work was to examine the surface of the enamel after debonding and final polishing. For such purpose the image magnification was used, by means of an optical microscope of coaxial light. The sample included the analysis of 10 upper arches of patients in the final of treatmente.

Thermal imaging of the pulp during residual adhesive removal.

OBJECTIVE: The aim of this study was to evaluate the temperature changes of the pulpal area during different adhesive clean-up procedures. MATERIALS AND METHODS: A total of 80 freshly extracted adult maxillary premolar teeth were divided into four groups. Adhesive clean-up was performed with 6- and 12-fluted tungsten carbide burs (TCB) using low- and high-speed handpieces with air or water cooling after bracket debonding. The temperature changes and cool down times were evaluated with a thermal camera. Paired t test, analysis of variance (ANOVA), and Student-Newman-Keuls multiple comparison analysis were used for statistical analysis of the data. RESULTS: All experimental groups, except the water cooling group, showed a significant temperature rise (p < 0.001) after residual adhesive removal. Only the 6-fluted TCB group with air cooling using a high-speed handpiece exceeded the critical 5.5 °C threshold value (5.91 ± 0.89 °C); this group also exhibited the longest cool down time to initial temperature (71.95 ± 13.68 s). The smallest temperature rise (0.48 ± 0.90 °C) and shortest cooling time value (11.90 ± 5.3 s) were measured in the 6-fluted TCB group with water cooling using a high-speed handpiece. CONCLUSION: Appropriate cooling procedures and fine tungsten carbide burs should be used during the removal of remnant adhesives after bracket debonding in order to prevent adverse pulpal reactions.

Efficacy of auxiliary devices for removal of fluorescent residue after bracket debonding.

OBJECTIVE: To evaluate four protocols for removal of fluorescent materials after bracket debonding. MATERIALS AND METHODS: Resin removal from 40 bovine enamel surfaces was performed according to groups (n = 10): conventional (C), white LED (W), LED that evidenced fluorescence (F), and fluorescent lens (FL). The following analyses were performed: sample thickness, superficial area of resin residue, and areas of resin residue or worn enamel in depth. ANOVA and Tukey tests were used to analyze sample thickness (P ≤ .05). Area measurements were analyzed by Kruskal-Wallis and Dunn's tests (P ≤ .05). RESULTS: The FL group showed the highest reduction in enamel thickness. F group final thickness was similar to that of other groups. The largest superficial areas of resin residue were found for the C and W groups, while the FL group had the greatest removal of resin residue. The C group exhibited the largest area in depth of resin residue. The FL and F groups exhibited the most loss of enamel with the least amount of resin residue; in contrast, the C and W groups presented the fewest areas of worn enamel and the most areas of resin residue. CONCLUSION: Auxiliary devices were useful for removal of fluorescent residue after bracket debonding.

Microbiological assessment of aerosol generated during debond of fixed orthodontic appliances.

INTRODUCTION: The aims of this study were to describe bacterial load and diversity of the aerosol created during enamel cleanup after the removal of fixed orthodontic appliances and to assess the effect of a preprocedural mouth rinse. METHODS: The study involved the sampling of ambient air adjacent to the patient's mouth during adhesive removal using a slow-speed handpiece and a spiral fluted tungsten carbide bur without water irrigation. Sampling was carried out during enamel cleanup with or without a preprocedural mouth rinse of either sterile water or chlorhexidine. Airborne particles were collected using a viable inertial impactor simulating the human respiratory tree. The bacteria collected were analyzed using both culture and molecular techniques. RESULTS: Bacteria produced during debond and enamel cleanup can reach all levels of the respiratory tree. The use of a preprocedural mouth rinse, either sterile water or chlorhexidine, increased the numbers and diversity of the bacteria in the air. CONCLUSIONS: When using a slow-speed handpiece and a spiral fluted tungsten carbide bur for enamel cleanup after orthodontic treatment, the bacterial load and diversity of the aerosol produced are lower when a preprocedural mouth rinse is not used.

Ceramic bracket debonding with Tm:fiber laser.

Lasers have the potential for reducing the required debonding force and can prevent the mechanical damage given to the enamel surface as a result of conventional debonding procedure. However, excessive thermal effects limit the use of lasers for debonding purposes. The aim of this study was to investigate the optimal parameters of 1940-nm Tm:fiber laser for debonding ceramic brackets. Pulling force and intrapulpal temperature measurements were done during laser irradiation simultaneously. A laser beam was delivered in two different modes: scanning the fiber tip on the bracket surface with a Z shape movement or direct application of the fiber tip at one point in the center of the bracket. Results showed that debonding force could be decreased significantly compared to the control samples, in which brackets were debonded by only mechanical force. Intrapulpal temperature was kept equal or under the 5.5°C threshold value of probable thermal damage to pulp. Scanning was found to have no extra contribution to the process. It was concluded that using 1940-nm Tm:fiber laser would facilitate the debonding of ceramic brackets and can be proposed as a promising debonding tool with all the advantageous aspects of fiber lasers.

The Use of the Er:YAG Laser for Bracket Debonding and Its Effect on Enamel Damage.

OBJECTIVE: The aim of the study was to evaluate the influence of Er:YAG laser irradiation on the debonding of metal and ceramic brackets and enamel damage ex vivo. BACKGROUND DATA: The principle of safe bracket debonding is to degrade the adhesive resin strength connecting the tooth and bracket. Removal of adhesive resin from tooth surfaces without iatrogenic damage (enamel loss) is generally the main problem of the otherwise very successful method of aesthetic straightening of teeth. METHODS: Forty ceramic and metal brackets (Clarity™ Advanced and Victory Series™; 3M Unitek, Monrovia, CA) were standardly bonded to buccal polished enamel surfaces of 30 caries-free human third molars. Two types of adhesive resins (Transbond™ XT Light Cure Adhesive; 3M Unitek, and Variolink II Professional Set; Ivoclar Vivadent AG) were used. Before debonding, the brackets in the laser group were irradiated with the Er:YAG laser (FJFI CVUT) 280 mJ, 250 µs long, repetition rate 6 Hz, spot focus 1 mm, and 140 sec. The control group was debonded without the laser irradiation. During the bracket irradiation, temperature changes inside the tooth were monitored using a thermal image infrared camera. The enamel surface was investigated by SEM. RESULTS: It has been observed that bracket removal was easier after the Er:YAG laser irradiation, and temperature rise was limited (from 2.0°C to 3.2°C) also for metal brackets. As against the nonirradiated samples, SEM investigation has confirmed no damage to enamel. CONCLUSIONS: Irradiation with Er:YAG laser radiation before debonding of ceramic brackets significantly decreases the bonding failure and amount of remaining adhesive.

Comparison of traditional orthodontic polishing systems with novel non-orthodontic methods for residual adhesive removal.

BACKGROUND: Following the debonding of orthodontic brackets, the removal of residual adhesive from the enamel surface is required. Published adhesive removal protocols present conflicting advice. AIMS: The present study evaluated the surface roughness of enamel after debonding and instrumentation with non-traditional orthodontic polishing systems. METHODS: The facial aspects of 35 extracted human incisor teeth were scanned with a surface profilometer for surface roughness prior to the bonding of orthodontic brackets. After debonding, residual adhesive was removed with a 12-fluted titanium carbide bur. The teeth were randomly divided into seven groups (N = 5 per group) and the enamel surface was polished with one of seven products. All samples were re-scanned for surface roughness and subjectively evaluated via SEM. RESULTS: There was no significant difference in enamel surface roughness between the groups when compared using surface profilometry. Visual observations from the SEM evaluations demonstrated differences in the enamel surface at the microscopic level that were not detected by profilometric analysis. CONCLUSIONS: The present study found no statistically significant difference in mean enamel smoothness change from pretreatment to post-treatment between the seven polishing methods studied via profilometer surface reading measurements. An SEM analysis showed visual differences in enamel striations viewed at 1000x magnification in a comparison of traditional versus non- traditional polishing methods.

Is There a Correlation Between Tensile Strength and Retrievability of Cemented Implant-Retained Crowns Using Artificial Aging?

PURPOSE: The main goal of this in-vitro study was to evaluate whether tensile strength and retrievability of cemented implant-retained crowns correlate when using artificial aging. MATERIALS AND METHODS: A total of 128 crowns were fabricated from a cobalt-chromium alloy for 128 tapered titanium abutments (6 degrees taper, 4.3 mm diameter, 4 mm length, Camlog). The crowns were cemented with glass-ionomer (Ketac Cem, 3M) or resin cements (Multilink Implant, Telio CS Cem [Ivoclar Vivadent], Retrieve [Parkell]). Multilink Implant was used without priming. The experimental groups were subjected to either 37,500 thermal cycles between 5°C and 55°C, 1,200,000 chewing cycles, or a combination of both. Control groups were stored for 10 days in deionized water. The crowns were removed with a universal testing machine or a clinically used removal device (Coronaflex, KaVo). Data were statistically analyzed using nonparametrical tests. RESULTS: Retention values were recorded between 31 N and 362 N. Telio CS Cem showed the lowest retention values, followed by Retrieve, Ketac Cem, and Multilink Implant (P≤.0001). The number of removal attempts with the Coronaflex were not significantly different between the cements (P>.05). Thermal cycling and chewing simulation significantly influenced the retrieval of Retrieve Telio CS Cem, and Ketac Cem specimens (P≤.05). Only for Multilink Implant and Telio CS Cem correlations between removal with the universal testing machine and the Coronaflex could be revealed (P≤.0001). CONCLUSIONS: Ketac Cem and Multilink Implant (without silane) can be used for a semipermanent cementation. Retrieve and Telio CS Cem are recommendable for a temporary cementation.

Efficiency of different protocols for enamel clean-up after bracket debonding: an in vitro study.

OBJECTIVE: This study aimed to assess the efficiency of six protocols for cleaning-up tooth enamel after bracket debonding. METHODS: A total of 60 premolars were divided into six groups, according to the tools used for clean-up: 12-blade bur at low speed (G12L), 12-blade bur at high speed (G12H), 30-blade bur at low speed (G30L), DU10CO ORTHO polisher (GDU), Renew System (GR) and Diagloss polisher (GD). Mean roughness (Ra) and mean roughness depth (Rz) of enamel surface were analyzed with a profilometer. Paired t-test was used to assess Ra and Rz before and after enamel clean-up. ANOVA/Tukey tests were used for intergroup comparison. The duration of removal procedures was recorded. The association between time and variation in enamel roughness (∆Ra, ∆Rz) were evaluated by Pearson's correlation test. Enamel topography was assessed by scanning electron microscopy (SEM). RESULTS: In Groups G12L and G12H, original enamel roughness did not change significantly. In Groups G30L, GDU, GR and GD, a smoother surface (p < 0.05) was found after clean-up. In Groups G30L and GD, the protocols used were more time-consuming than those used in the other groups. Negative and moderate correlation was observed between time and (∆Ra, ∆Rz); Ra and (∆Ra, ∆Rz); Rz (r = - 0.445, r = - 0.475, p < 0.01). CONCLUSION: All enamel clean-up protocols were efficient because they did not result in increased surface roughness. The longer the time spent performing the protocol, the lower the surface roughness.

Efficiency of different protocols for enamel clean-up after bracket debonding: an in vitro study

Objective: This study aimed to assess the efficiency of six protocols for cleaning-up tooth enamel after bracket debonding.Methods:A total of 60 premolars were divided into six groups, according to the tools used for clean-up: 12-blade bur at low speed (G12L), 12-blade bur at high speed (G12H), 30-blade bur at low speed (G30L), DU10CO ORTHO polisher (GDU), Renew System (GR) and Diagloss polisher (GD). Mean roughness (Ra) and mean roughness depth (Rz) of enamel surface were analyzed with a profilometer. Paired t-test was used to assess Ra and Rz before and after enamel clean-up. ANOVA/Tukey tests were used for intergroup comparison. The duration of removal procedures was recorded. The association between time and variation in enamel roughness (∆Ra, ∆Rz) were evaluated by Pearson's correlation test. Enamel topography was assessed by scanning electron microscopy (SEM).Results:In Groups G12L and G12H, original enamel roughness did not change significantly. In Groups G30L, GDU, GR and GD, a smoother surface (p < 0.05) was found after clean-up. In Groups G30L and GD, the protocols used were more time-consuming than those used in the other groups. Negative and moderate correlation was observed between time and (∆Ra, ∆Rz); Ra and (∆Ra, ∆Rz); Rz (r = - 0.445, r = - 0.475, p < 0.01).Conclusion:All enamel clean-up protocols were efficient because they did not result in increased surface roughness. The longer the time spent performing the protocol, the lower the surface roughness.

Objetivo: esse estudo objetivou avaliar a eficiência de seis protocolos de remoção de resina do esmalte após a descolagem de braquetes.Métodos:sessenta (60) pré-molares foram divididos em seis grupos conforme as ferramentas utilizadas: broca de 12 lâminas em baixa rotação (G12L), broca de 12 lâminas em alta rotação (G12H), broca de 30 lâminas em baixa rotação (G30L), polidor DU10CO-ORTHO (GDU), Renew System (GR) e polidor Diagloss (GD). As médias de rugosidade (Ra) e profundidade média de rugosidade (Rz) da superfície do esmalte foram analisadas com perfilômetro. Teste t pareado foi utilizado para avaliar Ra e Rz antes e depois da limpeza do esmalte; testes de ANOVA/Tukey foram utilizados para avaliar a diferença intergrupos. A duração dos procedimentos de remoção da resina foi registrada. Ainda, a associação entre o tempo e a variação da rugosidade do esmalte (ΔRa, ΔRz) foi avaliada pelo teste de correlação de Pearson. A topografia do esmalte também foi avaliada, por microscopia eletrônica de varredura (MEV).Resultados:nos grupos G12L e G12H, a rugosidade do esmalte original não se alterou significativamente. Nos Grupos G30L, GDU, GR e GD, foi verificada superfície mais lisa após a limpeza (p< 0,05). Nos Grupos G30L e GD, os protocolos utilizados foram mais demorados que nos demais grupos. Foi observada correlação negativa e moderada entre tempo, ΔRa e ΔRz (r = -0.445, r = -0.475, p< 0,01).Conclusão:todos os protocolos de limpeza do esmalte foram eficientes, pois não resultaram no aumento da rugosidade superficial. Quanto maior o tempo gasto, menor a rugosidade da superfície.

What is the best method for debonding metallic brackets from the patient's perspective?

BACKGROUND: The aim of this clinical investigation was to compare the level of discomfort reported by patients during the removal of orthodontic metallic brackets performed with four different debonding instruments. METHODS: The sample examined in this split-mouth study comprised a total of 70 patients (840 teeth). Four different methods of bracket removal were used: lift-off debonding instrument (LODI), straight cutter plier (SC), how plier (HP), and bracket removal plier (BRP). Prior to debonding with all experimental methods, the archwire was removed. Before appliance removal, each patient was instructed about the study objectives. It was explained that at the end of debonding in each quadrant, it would be necessary to assess the discomfort of the procedure using a visual analog scale (VAS). This scale was composed of a millimeter ruler scoring from 0 to 10, in which 0 = a lot of pain, 5 = moderate pain, and 10 = painless. The level of significance was predetermined at 5 % (p = 0.05), and the data were analyzed using the BioEstat 5.0 software (BioEstat, Belém, Brazil). RESULTS: The pain scores with SC were significantly higher than in all other methods. There were no significant differences between HP and BRP pain scores, and the LODI group showed the lowest pain scores. Statistically, significant differences were observed in the ARI between the four debonding methods. LIMITATIONS: The biggest limitation of this study is that each tooth was not assessed individually. CONCLUSIONS: Patients reported lower levels of pain and discomfort when metallic brackets were removed with the LODI. The use of a straight cutter plier caused the highest pain and discomfort scores during debonding.

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.

Enamel surface evaluation after bracket debonding and different resin removal methods.

OBJECTIVE: To assess enamel surface under scanning electron microscopy (SEM) after resin removal and enamel polishing procedures following brackets debonding, as well as compare the time required for these procedures. METHODS: A total of 180 deciduous bovine incisors were used. The enamel surface of each tooth was prepared and brackets were bonded with light cured Transbond XT composite resin. Brackets were removed in a testing machine. The samples were randomized and equally distributed into nine groups according to the resin removal and polishing technique: Group 1, 30-blade tungsten carbide bur in high speed; Group 2, 30-blade tungsten carbide bur in high speed followed by a sequence of 4 Sof-lex polishing discs (3M); Group 3, 30-blade tungsten carbide bur in high speed followed by Enhance tips (Dentsply). All groups were subdivided into (a) unpolished; (b) polished with aluminum oxide paste; and (c) polished with water slurry of fine pumice. Subsequently, the enamel surface was assessed and statistical analysis was carried out. RESULTS: There were statistically significant differences in enamel roughness and removal time among all groups. Groups 3a, 3b and 3c appeared to be the most efficient methods of removing resin with low damages to enamel. Groups 2a, 2b and 2c were the most time consuming procedures, and Group 2a caused more damages to enamel. CONCLUSION: The suggested protocol for resin removal is the 30-blade tungsten carbide bur in high speed followed by Enhance tips and polishing with aluminum oxide paste. This procedure seems to produce less damages and is less time consuming.

An alternative approach to debonding lingual brackets.

This clinical pearl describes a technique of debonding the lingual brackets with minimum discomfort to the patient. It also reduces the risk of swallowing or aspirating the brackets and decreases the risk of enamel damage.

Enamel surface evaluation after bracket debonding and different resin removal methods

OBJECTIVE: To assess enamel surface under scanning electron microscopy (SEM) after resin removal and enamel polishing procedures following brackets debonding, as well as compare the time required for these procedures. METHODS: A total of 180 deciduous bovine incisors were used. The enamel surface of each tooth was prepared and brackets were bonded with light cured Transbond XT composite resin. Brackets were removed in a testing machine. The samples were randomized and equally distributed into nine groups according to the resin removal and polishing technique: Group 1, 30-blade tungsten carbide bur in high speed; Group 2, 30-blade tungsten carbide bur in high speed followed by a sequence of 4 Sof-lex polishing discs (3M); Group 3, 30-blade tungsten carbide bur in high speed followed by Enhance tips (Dentsply). All groups were subdivided into (a) unpolished; (b) polished with aluminum oxide paste; and (c) polished with water slurry of fine pumice. Subsequently, the enamel surface was assessed and statistical analysis was carried out. RESULTS: There were statistically significant differences in enamel roughness and removal time among all groups. Groups 3a, 3b and 3c appeared to be the most efficient methods of removing resin with low damages to enamel. Groups 2a, 2b and 2c were the most time consuming procedures, and Group 2a caused more damages to enamel. CONCLUSION: The suggested protocol for resin removal is the 30-blade tungsten carbide bur in high speed followed by Enhance tips and polishing with aluminum oxide paste. This procedure seems to produce less damages and is less time consuming. .

OBJETIVO: avaliar a superfície do esmalte, por meio de microscopia eletrônica de varredura, após descolagem de braquetes e o polimento do esmalte, com diferentes técnicas de remoção de resina, bem como comparar o tempo necessário para a realização do procedimento. MÉTODOS: foram utilizados 180 dentes bovinos decíduos. A superfície do esmalte dos dentes foi preparada e realizada a colagem dos braquetes com resina Transbond XT. Os braquetes foram removidos em máquina de ensaio mecânico. Foram formados, aleatoriamente, nove grupos, de acordo com o tipo de remoção da resina e de polimento, sendo: Grupo 1, broca de tungstênio de 30 lâminas em alta rotação; Grupo 2, broca de tungstênio de 30 lâminas em alta rotação e sequência de quatro discos Soflex (3M); Grupo 3, broca de tungstênio de 30 lâminas em alta rotação e pontas de acabamento Enhance (Dentsply). Todos os grupos foram subdividido em (a) sem polimento, (b) polimento com pasta de óxido de alumínio e (c) polimento com pedra-pomes. As superfícies foram avaliadas e foi realizada análise estatística. RESULTADOS: houve diferença estatística entre os grupos em relação à rugosidade de superfície e ao tempo de remoção. Os grupos 3a, 3b e 3c demonstraram ser os métodos mais eficientes de remoção da resina, promovendo pouco dano à superfície do esmalte. Os grupos 2a, 2b e 2c consumiram maior tempo de procedimento, e o grupo 2a causou maior dano ao esmalte. CONCLUSÃO: sugere-se como protocolo de remoção o uso de broca de tungstênio de 30 lâminas para remoção do maior volume da resina, pontas de acabamento Enhance e polimento com a pasta de óxido de alumínio, por produzirem menor dano. .

In-vivo evaluation of the surface roughness and morphology of enamel after bracket removal and polishing by different techniques.

INTRODUCTION: The aim of this study was to evaluate the surface roughness and morphology of enamel with a surface roughness tester and scanning electron microscopy after the removal of metal brackets and polishing. METHODS: Ten orthodontic patients were selected for the study. At the conclusion of orthodontic treatment, their metal brackets were removed. For each patient, teeth on one side of the mouth were randomly chosen for finishing and polishing with aluminum oxide discs (n = 10). Teeth on the other side were finished with multilaminated carbide burs (n = 10). Dental replicas (before and after tooth polishing) were obtained with epoxy resin. Three surface roughness measurements were made in different directions with an angle of 120° among them, and a mean for each dental replica was calculated. The roughness data were statistically evaluated by repeated-measurements analysis of variance. Three specimens from each group were also used for scanning electron microscopy analysis. RESULTS: After resin removal, the average roughness in the carbide bur group (0.31 µm) was significantly greater than that in the aluminum oxide disc group (0.25 µm). CONCLUSIONS: The aluminum oxide disc polishing system resulted in less enamel roughness than did the multilaminated carbide bur system.

Polymerization shrinkage, modulus, and shrinkage stress related to tooth-restoration interfacial debonding in bulk-fill composites.

OBJECTIVES: The aim of the present study was to measure the polymerization shrinkage, modulus, and shrinkage stress of bulk-fill and conventional composites during polymerization and to investigate the relationship between tooth-composite interfacial debonding and shrinkage stress of the composites. METHODS: Polymerization shrinkage, dynamic modulus, and shrinkage stress of two high-viscosity bulk-fill (SonicFill (SF)/Tetric N-Ceram Bulk-Fill (TNB)) and two low-viscosity bulk-fill composites (Filtek Bulk-Fill (FB)/SureFil SDR Flow (SDR)) as well as one high-viscosity conventional (Filtek Z250 (Z250)) and one low-viscosity conventional composite (Filtek Z350 XT Flowable (Z350F)) were measured using custom-made instruments. Acoustic emission (AE) analysis was performed to evaluate the tooth-composite interfacial debonding during polymerization of the composites in Class 1 cavities on extracted third molars. RESULTS: The low-viscosity composites exhibited higher shrinkage and lower modulus than the high-viscosity composites. Polymerization shrinkage at 10 min ranged between 2.05% (SF) and 3.53% (Z350F). Polymerization shrinkage stress values at 10 min ranged between 1.68MPa (SDR) and 3.51MPa (Z350F). The number of AE events was highest in Z350F and lowest in SDR. CONCLUSIONS: Composites that exhibited greater polymerization shrinkage stress generated more tooth-composite interfacial debonding. In contrast to similar outcomes among the high-viscosity composites (conventional: Z250, bulk-fill: TNB and SF), the low-viscosity bulk-fill composites (FB and SDR) demonstrated better results in terms of polymerization shrinkage stress and tooth-composite interfacial debonding than did the low-viscosity conventional composite (Z350F). CLINICAL SIGNIFICANCE: Despite the better performance by some of the bulk-fill composites, clinicians should be aware that the bulk-fill composites are not perfect substitutes for conventional composites.