Efficacy of root-end filling techniques using premixed putty type bioceramic cements: an ex vivo study.

OBJECTIVES: Currently, premixed putty-type bioceramic cements (PPBCs) have become popular materials for root-end fillings. This study investigated three root-end filling techniques using PPBCs and calcium silicate-based sealers including EDTA pretreatment. MATERIALS AND METHODS: Ninety root segments were prepared and standardized with an artificial fin and lateral canal, and assigned to three groups (n = 30). Root-end fillings were placed using BC-RRM Putty alone (Group PA), injection of BC sealer followed by BC-RRM Putty (Lid Technique: Group LT) or BC-RRM Putty with BC sealer coating (Deep putty packing technique: Group DP). Half of each group was pretreated with 17% EDTA. The radiographic images of the specimens were assessed by five graders and push-out bond strength tests were conducted. The data were analyzed with a general linear model including two-way ANOVA and chi-square test at a significance level of 5%. RESULTS: DP approach demonstrated significantly higher bond strength than LT (P < 0.05). However, there was no statistically significant difference in bond strength between PA and either DP or LT. EDTA pretreatment had no significant effect on push-out bond strength. Radiographically, for the main canal, PA and DP scored significantly higher than LT. In the fin, PA scored significantly higher than others (P < 0.05). CONCLUSION: Our study highlights variations in root-end filling techniques. Injecting a bulk of bioceramic sealer before the placement of PPBCs may reduce bond strength and radiopacity. The application of PPBCs alone or in the deep putty technique demonstrates potential for favorable outcomes. EDTA pretreatment did not enhance bond-strength. CLINICAL RELEVANCE: Careful selection and application of bioceramic materials and techniques in root-end fillings may influence the outcome of endodontic root-end surgery. When PPBCs and calcium silicate-based sealers are used together for root-end fillings, sealer followed by deep putty application may offer improved bond strength and radiographic fill compared to the lid technique.

Effect of Material and Pad Abrasion on Shear Bond Strength of 3D-Printed Orthodontic Brackets.

OBJECTIVE: To investigate the effect of printing material and air abrasion of bracket pads on the shear bond strength of 3D-printed plastic orthodontic brackets when bonded to the enamel of extracted human teeth. MATERIALS AND METHODS: Premolar brackets were 3D-printed using the design of a commercially available plastic bracket in two biocompatible resins: Dental LT Resin and Dental SG Resin (n = 40/material). 3D-printed brackets and commercially manufactured plastic brackets were divided into two groups (n = 20/group), one of which was air abraded. All brackets were bonded to extracted human premolars, and shear bond strength tests were performed. The failure types of each sample were classified using a 5-category modified adhesive remnant index (ARI) scoring system. RESULTS: Bracket material and bracket pad surface treatment presented statistically significant effects for shear bond strengths, and a significant interaction effect between bracket material and bracket pad surface treatment was observed. The non-air abraded (NAA) SG group (8.87 ± 0.64 MPa) had a statistically significantly lower shear bond strength than the air abraded (AA) SG group (12.09 ± 1.23 MPa). In the manufactured brackets and LT Resin groups, the NAA and AA groups were not statistically significantly different within each resin. A significant effect of bracket material and bracket pad surface treatment on ARI score was observed, but no significant interaction effect between bracket material and pad treatment was found. CONCLUSION: 3D-printed orthodontic brackets presented clinically sufficient shear bond strengths both with and without AA prior to bonding. The effect of bracket pad AA on shear bond strength depends on the bracket material.

Optimizing teaching effectiveness in dental education for a new generation of learners.

PURPOSE: Today's dental students, Generation Z (Gen Z), are said to learn differently than those of previous generations. As generations of dental students vary, our teaching styles must keep up with unique and changing groups of individuals. METHODS: This article discusses learner-focused teaching methods including techniques that address the characteristics of Gen Z learners. Blended learning methods that combine online media with traditional face-to-face sessions, team-based learning, and a flipped classroom format have previously been suggested as ways to increase learning effectiveness and student satisfaction. RESULTS: In this paper, the characteristics and preferences of Gen Z students are described along with the challenges they create with conventional teaching methods. An implementation strategy using principles from organizational agility and Bolman and Deal's Four Frames Model is proposed for dental schools to transition to a more learner-centered teaching approach. CONCLUSIONS: The suggested strategy can be customized and could be useful to schools that wish to enhance their teaching methods to meet the learning needs of Gen Z dental students and beyond.

Fracture resistance of cement-retained and screw-cement-retained milled posterior crowns with screw-access hole preparations before and after firing: An in vitro study.

STATEMENT OF PROBLEM: When a cement-retained lithium disilicate crown needs to be removed, perforation is needed to reach the abutment screw. How this process affects its strength is unclear. PURPOSE: The purpose of this in vitro study was to evaluate the fracture strength of milled lithium disilicate implant crowns with screw-access holes created before and after the firing stages. MATERIAL AND METHODS: Nine implant replicas with stock abutments were embedded in acrylic resin. Forty-five lithium disilicate (IPS e.max CAD) crowns were designed, milled, and divided into groups. The control group had no screw access, the blue state group had the screw access created in the intermediate phase of the ceramic, and the postfiring group had the screw access created after firing. The crowns were cemented with a self-adhesive resin cement, placed in an incubator for 24 hours and then thermocycled. The screw-access holes were sealed with composite resin. The crowns were loaded to failure with a universal testing machine using a 1- mm-diameter ball at a crosshead speed of 0.5 mm/min and a 5-kN cell load. Data were analyzed by ANOVA and the Tukey post hoc test (α=.05). RESULTS: Screw-access holes created before and after firing stages had a significant effect on the fracture resistance of lithium disilicate crowns (P=.002). No difference in fracture resistance was observed between the control group and the blue state group (P>.05), while the fracture resistance of the postfiring group was significantly lower than that of the control group and the blue state group (P<.05). CONCLUSIONS: The fracture strength of lithium disilicate crowns was not affected by a screw-access hole created during the blue state of the ceramic followed by repair with composite resin. Creating a screw-access hole after firing the ceramic reduced fracture strength.

Evaluation of the dimensional accuracy of thermoformed appliances taken from 3D printed models with varied shell thicknesses: An in vitro study.

OBJECTIVE: Clinicians make numerous decisions when 3D printing models for fabrication of thermoformed appliances, including printing solid or hollow models. While hollow models can reduce resin use, models intended for thermoformed appliance fabrication must be printed with sufficient thickness to withstand thermoforming. The aim of the study was to determine for hollow 3D printed orthodontic models if there is an effect of shell thickness on the dimensional accuracy of retainers thermoformed upon them as compared with solid models and, if so, to identify the minimum shell thickness that ensures dimensional accuracy of the thermoformed retainer under the conditions investigated. MATERIAL AND METHODS: Thermoformed appliances were fabricated on 3D printed models of six shell thicknesses: 1.0mm, 1.5mm, 2.0mm, 2.5mm, 3.0mm, and solid (n=10/group). The models were scanned before and after thermoforming. Thermoformed appliances were captured by two methods: scanning a polyvinylsiloxane casting of the appliance and scanning the appliance interior surface (intaglio surface). Each model-appliance pair was compared using superimposition software. A generalized linear model and post-hoc Tukey contrasts (α=0.05) were applied to compare each thickness. RESULTS: Model thickness has a statistically significant effect on dimensional accuracy of thermoformed appliances. Appliances fabricated on 1.0mm and 1.5mm models displayed poor accuracy, with a statistically significantly lower percentage of data points within tolerance (±0.250mm) than appliances fabricated on models printed at 2.0mm thickness and greater. CONCLUSIONS: 3D printed model thickness affects the dimensional accuracy of a thermoformed retainer. To ensure minimal deformation and promote clinical utility of the thermoformed appliance, models should be printed with a minimum shell thickness of 2.0mm for the materials investigated.

Wear Resistance of 3D Printed and Prefabricated Denture Teeth Opposing Zirconia.

PURPOSE: To evaluate the wear resistance of a recently developed three-dimensional (3D) printed denture teeth resin compared to three commercially available prefabricated denture teeth. MATERIALS AND METHODS: A total of 88 maxillary first molar denture teeth were evaluated: C (Classic; Dentsply Sirona, York, PA), DCL (SR Postaris DCL; Ivoclar Vivadent, Schaan, Liechtenstein), IPN (Portrait IPN; Dentsply Sirona, York, PA), and F (Denture Teeth A2 Resin 1 L; Formlabs, Somerville, MA). The 3D printed denture tooth specimens were fabricated from a methacrylate-based photopolymerizing resin using stereolithography (SLA). Denture teeth were subjected to a three-body wear test with a poly(methylmethacrylate) (PMMA) abrasive slurry. A Leinfelder-style four station wear apparatus with custom bullet-shaped milled zirconia styli was utilized with a load force of 36-40 N at 1.7 Hz for 200,000 cycles. Maximum depth of wear was measured using a lab grade scanner and analyzing software program. Data were analyzed using a one-way ANOVA followed by the Tukey's Multiple Comparisons post hoc test (α = 0.05). RESULTS: A statistically significant difference in depth of wear was found between denture tooth materials (p < 0.001). The mean vertical depth of wear for the 3D printed denture teeth (0.016 ± 0.010 mm) was statistically significantly less than the prefabricated denture teeth. The highly cross-linked denture teeth, DCL (0.036 ± 0.011 mm) and IPN (0.035 ± 0.014 mm), exhibited statistically significantly less wear than the conventional acrylic denture teeth. The conventional acrylic denture teeth demonstrated the greatest wear (0.058 ± 0.014 mm). No significant difference in depth of wear was found between DCL and IPN (p > 0.001). CONCLUSIONS: Denture tooth material significantly influences the depth of wear. The 3D printed denture teeth demonstrated superior wear resistance compared to the commercially available prefabricated denture teeth when opposed to zirconia. Denture teeth fabricated with SLA technology may have a promising future in prosthetic dentistry.

Gloss and Surface Roughness of Anterior Pediatric Zirconia Crowns.

PURPOSE: The purpose of this study was to determine gloss and surface roughness (Ra) of pediatric anterior zirconia crowns. METHODS: Gloss of labial and lingual surfaces of pediatric anterior zirconia crowns from three manufacturers was measured on 20 specimens using a small area gloss meter on each. Ra (µm) was measured using a contact-type surface profilometer. Data were evaluated by analysis of variance and pair-wise comparison at the 0.05 level of significance. RESULTS: There were statistically significant interactions between surface location and crown type for both gloss and Ra scores. NuSmile had higher mean gloss scores and lower mean Ra scores than both Kinder Krowns and EZCrowns. Kinder Krowns showed lower mean gloss scores and higher Ra scores than other crown groups. CONCLUSION: Among all crowns, there was a trend of higher mean gloss paired with lower mean surface roughness, and lower mean gloss paired with higher mean Ra. Hand smoothed followed by mechanically polished zirconia crowns (NuSmile) displayed the highest mean gloss and lowest mean Ra compared to hybrid polishedglazed zirconia crowns (Kinder Krowns, EZCrowns). Of the hybrid polished-glazed zirconia crowns, Kinder Krowns displayed the lowest mean gloss and highest mean Ra.

Accuracy and mechanical properties of orthodontic models printed 3-dimensionally from calcium sulfate before and after various postprinting treatments.

INTRODUCTION: Dental models fabricated with 3-dimensional printing technologies are revolutionizing the practice of orthodontics, but they generally comprise polymeric materials that may not be suitable for certain applications, such as soldering appliances. The objective of this study was to investigate the dimensional accuracy and mechanical properties of 3-dimensional printed ceramic-based models before and after various treatments intended to improve their mechanical properties. METHODS: Thirty identical models were printed 3-dimensionally from a calcium sulfate-based substrate and divided into 3 groups for treatment: high heat (250°C for 30 minutes), low heat (150°C for 30 minutes), and Epsom salt treatment. Each model was scanned before and after treatment with a laser scanner, and dimensional stability was analyzed by digital superimpositions using a best-fit algorithm. The models were weighed before and after treatment to evaluate mass changes. Additionally, 3-dimensional printed cylinders treated as described above and an untreated control group were subjected to compressive mechanical testing (n = 11 per group). RESULTS: The Epsom salt treatment group had statistically significant increases in both peak compressive stress and modulus of elasticity when compared with the other treatment groups. All treatment groups had statistically significant changes in mass, with the Epsom salt group gaining mass and the 2 heat-treatment groups losing mass. The low-temperature treatment group had a statistically significantly lower mean average for dimensional deviations (0.026 ± 0.010 mm) than did the other treatment groups (0.069 ± 0.006 and 0.059 ± 0.010 mm for high temperature and Epsom salt, respectively). CONCLUSIONS: Dental models printed 3-dimensionally with calcium sulfate and treated with Epsom salt showed significant improvement in compressive mechanical properties and retained clinically acceptable dimensional stability.

Influence of light source, polarization, education, and training on shade matching quality.

STATEMENT OF PROBLEM: Many factors influence the quality of shade selection, and isolating how significantly each of these factors influences results is difficult. PURPOSE: The purpose of this in vitro study was to compare results of shade matching using handheld lights with or without a polarizing filter with results obtained using a professional viewing booth and to analyze the influence of education and training on shade selection outcome. MATERIAL AND METHODS: A total of 96 third-year dental students (evaluators) were randomly separated into 4 groups. Each group was assigned 1 of 2 handheld shade-matching devices (lights) with or without a polarizing filter. Each group performed a shade matching exercise using the handheld light or a professional viewing booth. The exercise consisted of matching shade tabs placed in a typodont to a commercial shade guide. Each group repeated this procedure 4 times over a 9-week period. A lecture on shade matching was presented at the fifth week of the study, between "before" and "after" shade matching procedures. RESULTS: Shade matching scores with handheld lights (7.8) were higher than scores of shade matching with the viewing booth (7.2). The mean scores for before (7.2) and after (7.8) shade matching (with education and training in between) were significantly different. The combined effect of light and education and training improved the shade matching score by 1.2, from 6.8 in the before sessions using the viewing booth to 8.0 in the after sessions using handheld lights. A 21% increase in the number of evaluators who selected 1 of 4 best matches was recorded, 10% for handheld lights versus viewing booth after education and training versus before sessions and 11% between after sessions using handheld lights versus before sessions using viewing booth. CONCLUSIONS: Within the limits of the study, the shade matching scores with handheld lights were significantly better than the results obtained using a viewing booth (P<.01). Using a handheld light with or without a polarizing filter did not influence shade matching results. Mean shade matching scores were significantly better after education and training (P<.01). Light combined with education and training resulted in the greatest increase in shade matching quality.

Evaluation of a calcium silicate-based cement as a root reinforcement material for endodontically treated maxillary anterior teeth.

STATEMENT OF PROBLEM: Fractures of endodontically treated teeth have been attributed to weakened tooth structure caused by root canal enlargement and post preparation. PURPOSE: The purpose of this in vitro study was to evaluate the fracture resistance of roots filled with either gutta percha, composite resin (LuxaCore Dual), or calcium silicate-based cement (Biodentine). MATERIAL AND METHODS: One hundred twenty freshly extracted, human, permanent maxillary anterior teeth were sorted by type and assigned to 1 of 4 groups (n=30). The teeth in group NT were not endodontically treated and served as the control. The teeth in groups GP, LC, and, BD were accessed and instrumented to size 40/06. In group GP, the root canals were completely filled with gutta percha. In groups LC and BD, only the apical 5-mm portion of the root canals was filled with gutta percha, and the remaining portion of the root canals was filled with (LuxaCore Dual) in group LC and with (Biodentine) in group BD. Fracture resistance (kN) was assessed at the middle portion of each root, using a 3-point bending test with a universal testing machine exerting a compressive load on a loading pin at a crosshead speed of 0.5 mm/min until fracture occurred. One-way ANOVA was used to compare the mean root fracture resistance among the 4 groups (α=.05). RESULTS: The mean ± SD fracture loads were 2.13 ±0.53 kN for group NT, 1.97 ±0.60 kN for group GP, 2.18 ±0.71 kN for group LC, and 2.22 ±0.54 kN for group BD. No statistically significant differences were found among the 4 groups (P>.05). CONCLUSIONS: The roots of endodontically treated maxillary anterior permanent incisors filled with gutta percha, Biodentine, or LuxaCore Dual had resistance to fracture similar to that of teeth that were not endodontically treated.

Accelerated aging effects on color and translucency of flowable composites.

OBJECTIVES: To evaluate the effect of accelerated aging on color and translucency parameter of composites. MATERIALS AND METHODS: Filtek Supreme Ultra Flowable, shades A1, A3, White, Tetric EvoFlow, shades A1, A3, Bleach, and Filtek Z250 shades A1, A3, B1 were evaluated. Color and translucency were recorded using a spectrophotometer after 24-hour storage (baseline) and after accelerated aging. The data were analyzed by analysis of variance. RESULTS: Fisher's PLSD intervals for comparisons among products and shades were 0.4, 0.1, 0.3, and 0.4 for ΔL*, Δa*, Δb*, and ΔE*, respectively. The data showed significant ΔE* and ΔL* main effects for composite product and shades (p < 0.001) and their interactions (p = 0.008 and p = 0.03), respectively. Tetric EvoFlow displayed the smallest aging-dependent color shift followed by Filtek Z250 and Filtek Supreme Ultra Flowable. Accelerated aging did not significantly affected the composites for translucency (p > 0.05). CONCLUSION: The effects of aging on color of resin composites were composite and shade dependent. Translucency was not affected by accelerated aging. CLINICAL SIGNIFICANCE: The effects of aging on color of resin composites were composite and shade dependent.

Effects of repeated sterilization cycles on primary stability of orthodontic mini-screws.

OBJECTIVE: To determine if repeated sterilization has deleterious effects on the clinical stability of mini-screws. MATERIALS AND METHODS: Thirty each of the following mini-screws were tested: Aarhus (American Orthodontics, Sheboygan, Wisc), VectorTAS (Ormco Corporation, Orange, Calif), Dual-Top (RMO, Denver, Colo), and Ortho Anchor (KLS Martin, Jacksonville, Fla). Controls were sterilized once using a steam autoclave (Statim 5000, SciCan USA, Canonsburg, Pa). Each group of mini-screws was divided into three groups: the control (n = 10) and two test groups (n  =10, each). Test groups were cycled five and 10 times respectively. All screws were inserted into custom-designed synthetic blocks that simulated mandibular bone. Maximum insertion torque and lateral displacement force data were recorded and subjected to statistical testing. Two-way analysis of variance (ANOVA) and three-way mixed ANOVA were used for statistical analyses for maximum insertion torque data and lateral displacement force data, respectively. Level of significance was established at P < .05. RESULTS: Insertion torque values displayed significant differences between both of the groups and sterilization cycles (P < .05). Significant differences were observed between American Aarhus mini-screws and both RMO and KLS Martin mini-screws. Ormco Vector mini-screws also differed significantly from the KLS Martin mini-screws in this comparison (P < .05). For lateral displacement, there was a significant main effect of groups, F(1,36) = 14.5 (P < .05). Significant differences were observed between American Aarhus mini-screws and all three of the other groups (P < .05). CONCLUSIONS: The examined groups displayed statistical differences of variable quality that may not affect their clinical stability.

Clinical effectiveness and sensitivity with overnight use of 22% carbamide peroxide gel.

OBJECTIVE: To evaluate clinical effectiveness, color rebound and sensitivity of 22% carbamide peroxide (CP) with 3% potassium nitrate. METHODS: Twenty-one participants were enrolled and treated overnight for 2 weeks with 22% CP (Venus White, Heraeus Kulzer). Visual color measurement was performed and expressed in shade guide units (SGU) of Vita Classical (VC) and Vita Bleachedguide 3D Master (BG) shade guides. Instrumental color measurements were performed using an intraoral spectrophotometer (Vita Easyshade Compact, EC). Color measurements were taken on a canine and central incisor at baseline, 2, 3, and 4 weeks. Participants documented sensitivity and data were analysed with Wilcoxon and Bonferroni correction at the 0.05 level of significance. RESULTS: Mean BG SGU difference immediately, 1 and 2 weeks postbleaching compared to baseline was 4.9 (2.1), 4.5 (2.2) and 4.6 (2.0), respectively. Corresponding VC values were 7.0 (3.5), 6.4 (3.3) and 6.5 (3.4), while corresponding ΔE* values were 8.3 (4.1), 8.1 (4.0) and 7.9 (3.5). For visual shade evaluation there was a significant decrease in SGU from baseline and each subsequent week, p<0.001. There was no difference between week 3 and week 4 using VC or BG. For instrumental color measurements, there was no difference from week 2 to week 3 for canines and generally no difference between week 3 and week 4 for incisors. CONCLUSIONS: Visual and instrumental evaluation showed rebound occurred 1 week postbleaching with 22% carbamide peroxide and 3% potassium nitrate. In general, color was stable at 2 weeks postbleaching. Participants reported low sensitivity levels with a mean value of below 2 on a 0-10 scale. CLINICAL SIGNIFICANCE: This study demonstrates efficacy with overnight usage of 22% carbamide peroxide with 3% potassium nitrate and demonstrates postbleaching color is stable at two weeks with low tooth sensitivity.

Latex and non-latex orthodontic elastic force loss due to cyclic temperature.

UNLABELLED: The purpose of this study was to compare the force loss of 1/4 inch (6.35mm) 3.5oz (99g) medium latex elastics from Ormco Corp. to non-latex elastics from ClassOne Orthodontics and Phoenix after being cycled between different temperatures. Elastics were stretched to 1.57 inches (40mm) on jigs and cycled in water baths for 4 minutes at 5 degrees C and 37 degrees C, 21 degrees C and 37 degrees C, 5 degrees C and 50 degrees C, 37 degrees C and 50 degrees C, and a control group was held at 3 degrees 7 degrees C. The force produced by new elastics and elastics after incubation was measured using a Mini 44 Instron. RESULTS: All elastics experienced increased force loss that correlated with increased temperatures with the exception of Ormco latex elastics. The latex elastics had the greatest force loss upon cycling between 5 degrees C and 50 degrees C while the non-latex elastics had the greatest force loss while cycling between 37 degrees C and 50 degrees C. All elastics were strongest when cycled between 5 degrees C and 37 degrees C. CONCLUSION: This study suggests that hot liquids reduce the force of latex and non-latex elastics even when cycled between hot temperatures for brief periods of time.

Bond strength comparison of color change adhesives for orthodontic bonding.

This study investigated whether three different color change light-cured orthodontic bonding adhesives have comparable shear bond strengths to a conventional light-cured orthodontic bonding adhesive. The sample of 240 bovine incisors was divided into four groups of 60 each. Each group tested one of four orthodontic bonding adhesives: 3M Unitek Transbond PLUS, Ormco Gréngloo, Ormco Blúgloo, and 3M Unitek Transbond XT (control). The four groups were further divided into two subgroups of 30 with shear bond strength tested at two different times (15 minutes and 24 hours) post-bond. The shear bond strength was measured on a universal testing machine. The data were analyzed by two-way analysis of variance and post-hoc comparisons (Fisher's PLSD) at the 0.05 level of significance. The average shear bond strength was greater at 24 hours than at 15 minutes for Transbond PLUS, Blúgloo, and Transbond XT. For Gréngloo, the average shear bond strength was greater at 15 minutes than at 24 hours. Gréngloo tested at 15 minutes had the highest average shear bond strength. Gréngloo tested at 24 hours had the lowest average shear bond strength. All four orthodontic bonding adhesives demonstrated bond strengths considered to be clinically acceptable for orthodontic purposes.

In-office vital bleaching with adjunct light.

The use of light as an adjunct to in-office bleaching is a controversial topic in dentistry because of the equivocal outcomes of the research conducted in studies using light compared with no light treatment. The proper diagnosis and treatment planning of discolored teeth is of primary importance when managing the outcomes and setting expectations for patients undergoing in-office bleaching with supplemental light. Although no study is conclusive on all bleaching lights, research evidence provides guidelines for the responsible use of in-office bleaching lights in dentistry.

Shear bond strengths of a selenium containing and a conventional light cured adhesive for orthodontic bonding.

BACKGROUND: The objectives of this study were to evaluate the debonding strength and mode of failure of a selenium containing adhesive compared to an established orthodontic adhesive. MATERIALS AND METHODS: One hundred sixty bovine mandibular incisors were allocated to eight groups: steel and clear brackets were bonded with either selenium containing adhesive (Group 1: SeLect Defense) or a conventional light-cured adhesive (Group 2:Transbond XT) to measure debond strength and the adhesive remnant index was used to assess the location of bond failure. Data was evaluated using a three-way analysis of variance and Fisher's PLSD multiple comparisons test for mean debond strengths. RESULTS: Group 2 debond strengths were greater than that of Group 1 with the steel and clear brackets. Group 1 debond strengths were greater with clear than with steel brackets at both time points. Both adhesives demonstrated increased debond strengths from zero to 24 hours and the clear brackets exhibited a greater ARI than steel after debonding. Comparisons of debond strength means among adhesives, brackets, and times were all statistically significant. CONCLUSIONS/DISCUSSION: All debond strengths were within a clinically acceptable range according to previous literature. SeLect Defense may be desirable due to its potential for preventing white spot lesions despite the reduced strength compared to Transbond XT.

Bond strength comparison of color-change adhesives for orthodontic bonding using a self-etching primer.

BACKGROUND: The purpose of this study was to compare the shear bond strengths of two color-change adhesives with a commonly used conventional light-cure adhesive while using a self-etching primer, and to compare any changes in shear bond strengths over time. METHODS: One hundred and eighty extracted bovine incisors were randomly divided into nine groups of 20 teeth each. The teeth were prepared with a self-etching primer (Transbond™ Plus) Metal lower incisor brackets were bonded directly to each tooth with two different color-change adhesives (TransbondPlus and Grengloo™) and a control (Transbond XT). The teeth were debonded at three different time points (15 minutes, 24 hours, 1 week) using an Instron at 1.0 mm/min. The teeth that were to be debonded at 24 hours and 1 week were stored in distilled water at 37°C to simulate the oral environment. The data were analyzed by two-way analysis of variance and with Fisher's protected least-significant difference multiple comparisons test at the P < 0.05 level of significance. Adhesive remnant index (ARI) scores were calculated for each debonded tooth. RESULTS: Transbond Plus at 1 week had the highest mean shear bond strength (14.7 mPa). Grengloo tested at 24 hours had the lowest mean shear bond strength (11.3 mPa). The mean shear bond strengths for the remaining seven groups had a range of 12-14.5 mPa. Grengloo had >80% samples presenting with an ARI score of 1 at all times. Interestingly, both Transbond groups had ARI scores of 3 in more than 50% of their samples. CONCLUSION: Time had no significant effect on the mean shear bond strength of Transbond XT, Grengloo, or Transbond Plus adhesive.