Silver diamine fluoride and bond strength to enamel in vitro: A pilot study.

PURPOSE: To evaluate if pre-treatment with silver diamine fluoride (SDF) adversely affects the bond strength of orthodontic brackets to enamel. METHODS: 30 extracted non-carious permanent molar teeth were embedded in acrylic resin cylinders with buccal surfaces exposed and randomly divided equally into two groups. The experimental enamel surfaces were treated with 38% SDF applied for 1 minute between phosphoric acid etch and metal orthodontic bracket bonding with Transbond XT Light Cure Adhesive. Control groups were treated with 37% phosphoric acid etch followed by bonding. All samples were subjected to 500 thermocycles between 5°C and 55°C prior to shear load testing. Mean values and standard deviations of shear bond strengths for each group were analyzed using a general linear model at P< 0.05. Characteristics of bond failure were also recorded via Adhesive Remnant Index (ARI) and analyzed using an ordinal logistic regression at P< 0.05. RESULTS: No significant difference in shear bond strength to enamel was observed between the control and experimental groups (P= 0.65). Comparison of ARI did demonstrate a significant difference between the groups (P= 0.013); SDF significantly altered the characteristic of bond failure, resulting in more adhesive remaining bonded to enamel after failure. No silver staining of treated surfaces was observed. CLINICAL SIGNIFICANCE: The application of SDF to etched non-carious enamel in vitro prior to orthodontic bracket bonding does not adversely affect bond strength.

Surface analysis of study models generated from OrthoCAD and cone-beam computed tomography imaging.

INTRODUCTION: The purpose of this research was to determine the accuracy of digital models generated by cone-beam computed tomography and compare it with that of OrthoCAD models (Cadent, Carlstadt, NJ) for orthodontic diagnosis and treatment planning by using surface area analysis. MATERIALS: Two sets of maxillary and mandibular digital models of 30 subjects were obtained. The models were made from impressions scanned with OrthoCAD and by conversion of related cone-beam computed tomography files. Each patient's matched pairs of maxillary and mandibular models were superimposed by using a software program and a best-fit algorithm; surface-to-surface analysis was then performed. The average linear differences between the 2 files at all points on the surfaces were measured, and tolerance levels of 0.25, 0.5, 0.75, 1.0, 1.25, and 1.5 mm were set to determine the surface correlation amounts between the 2 files. Additionally, 6 linear measurements from predetermined landmarks were also measured and analyzed. RESULTS: The average maxillary model linear difference was 0.28 to 0.60 mm, whereas the average mandibular model linear difference ranged between 0.34 and 0.61 mm. Greater than a 90% surface correlation was obtained on average at 1.00 mm in the maxillary models and at 1.25 mm in the mandibular models. The mean differences obtained from the linear measurements of the maxillary and mandibular models were 0.071 and 0.018 mm, respectively. CONCLUSIONS: Surface-to-surface analysis of OrthoCAD and digital models generated by cone-beam computed tomography pointed to a fair overlap between the protocols. The accuracy of digital models generated by cone-beam computed tomography is adequate for initial diagnosis and treatment planning in orthodontics.

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.

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.

Fluoride-releasing orthodontic adhesives and topical fluoride effect on enamel caries formation: an in vitro study.

PURPOSE: To examine in vitro orthodontic bonding sealants combined with daily fluoride (NaF) rinse on caries-like lesion depths. METHODS: Permanent molar teeth (n = 40) were randomly divided into four treatment groups: 1: Pro-Seal, 2: Light Bond, 3: Pro-Seal with NaF rinsing, and 4: Light Bond with NaF rinsing. Orthodontic sealant material was placed on buccal surfaces of each group and surrounded by acid-resistant varnish on the buccal and a control window on the lingual. Each group underwent synthetic saliva rinsing and lesion initiation. Groups 3 and 4 were subjected to 0.05% NaF for 1 minute per day. Artificial caries were created in vitro. The specimens in each treatment group were sectioned and mean lesion depth was assessed with polarized light microscopy (water imbibition). Lesion depth was compared among the treament groups using ANOVA and Duncan's Multiple Range Test. RESULTS: The ProSeal and Light Bond treatment groups exhibited significant reductions in mean lesion depths as compared to the controls (P < 0.05). ProSeal with NaF rinsing and Light Bond with NaF rinsing treatment groups exhibited significant reductions in mean lesion depth when compared to Pro Seal and Light Bond treatment without fluoride rinsing and controls (P < 0.05). The enamel-resin interfaces of all treatment groups were intact and exhibited no caries-like lesion formation.

Digital models vs plaster models using alginate and alginate substitute materials.

OBJECTIVE: To compare the dimensional stability of four impression materials over time and to compare OraMetrix digital models vs traditional plaster models. MATERIALS AND METHODS: Two traditional alginates (Identic and imprEssix) and two alginate substitutes (Alginot FS and Position PentaQuick) were used to take multiple impressions of a maxillary typodont. Fifteen impressions for each material were taken and poured with plaster at three time points: 72 hours, 120 hours, and 1 week. Five impressions for each material were taken and were sent to OrthoProof for digital model reproduction at 72 hours. Digital models were then integrated with OraMetrix software. Plaster and digital models were measured in the anterior-posterior, transverse, and vertical dimensions. The control typodont and plaster models were measured using a digital caliper, and digital models were measured using OraMetrix software. RESULTS: Statistically significant changes were found for models replicated from Identic impression material in all three dimensions by 72 hours. Statistically significant changes were seen in imprEssix impressions in the vertical and intercanine dimensions. Digital models were significantly smaller in all dimensions compared with plaster models and the control. CONCLUSIONS: Identic impression material showed a statistically and clinically significant change in all dimensions within 72 hours and therefore should not be used if impressions are not going to be poured immediately. Alginate substitutes were dimensionally stable over an extended period. Digital models produced by OraMetrix were not clinically acceptable compared with plaster models.

A comparison of shear bond strengths on bleached and unbleached bovine enamel.

INTRODUCTION: This study investigated whether tooth whitening with two different bleaching systems affects the shear bond strength achieved using an orthodontic self-etching primer. METHODS: The sample of 210 bovine incisors was divided into three groups. One group served as the control, while the other two groups received either an over-the-counter "white strip" bleaching regimen (Opalescence TresWhite) or a "power bleaching" in-office regimen (Opalescence Boost). Each bleaching group was divided into three groups to be tested at three time intervals post-bleaching: immediately, 24 hours, and 7 days. RESULTS: When compared to the control, the shear bond strength attained on Opalescence TresWhite treated specimens was not significantly lower at any time interval post-bleaching. Immediately after bleaching and 24 hours after bleaching, the Opalescence Boost treated groups showed significantly lower shear bond strengths than both the control groups and the Opalescence TresWhite groups. CONCLUSIONS: Bleaching with 38 percent hydrogen peroxide immediately and 24 hours before bonding reduced the shear bond strengths. After seven days the bond strengths were normal. Bleaching with 10 percent hydrogen peroxide in the form of white strip material did not reduce shear bond strengths.

Facial morphologies of an adult Egyptian population and an adult Houstonian white population compared using 3D imaging.

OBJECTIVE: To compare the facial morphologies of an adult Egyptian population with those of a Houstonian white population. MATERIALS AND METHODS: The three-dimensional (3D) images were acquired via a commercially available stereophotogrammetric camera capture system. The 3dMDface System photographed 186 subjects from two population groups (Egypt and Houston). All of the participants from both population groups were between 18 and 30 years of age and had no apparent facial anomalies. All facial images were overlaid and superimposed, and a complex mathematical algorithm was performed to generate a composite facial average (one male and one female) for each subgroup (EGY-M: Egyptian male subjects; EGY-F: Egyptian female subjects; HOU-M: Houstonian male subjects; and HOU-F: Houstonian female subjects). The computer-generated facial averages were superimposed based on a previously validated superimposition method, and the facial differences were evaluated and quantified. RESULTS: Distinct facial differences were evident between the subgroups evaluated, involving various regions of the face including the slant of the forehead, and the nasal, malar, and labial regions. Overall, the mean facial differences between the Egyptian and Houstonian female subjects were 1.33 +/- 0.93 mm, while the differences in Egyptian and Houstonian male subjects were 2.32 +/- 2.23 mm. The range of differences for the female population pairings and the male population pairings were 14.34 mm and 13.71 mm, respectively. CONCLUSIONS: The average adult Egyptian and white Houstonian face possess distinct differences. Different populations and ethnicities have different facial features and averages.

Force-deflection comparison of superelastic nickel-titanium archwires.

This in vitro study compared the force-deflection behavior of 6 superelastic nickel-titanium orthodontic archwires (0.016 x 0.022 in) under controlled moment and temperature. To simulate leveling, maxillary canine brackets and first molar tubes were bonded in such a manner as to remove the tip and angulation from the system. The wires (n = 10) were passively self-ligated into stainless steel brackets attached to an acrylic jig to simulate the maxillary arch. A testing machine recorded deactivations of 3 distances (5, 4, and 3 mm) at 37 degrees C in the canine position. Force-deflection measurements were recorded from the deactivations only. Forces produced during deactivation, at deflections of 2.5, 2.0, and 1.5 mm, were compared by analysis of variance. Significant differences (P < 0.0001) in forces were observed among the wires at the various deflections. All wires exhibited superelastic behavior, and rankings were derived according to statistically significant differences for each deflection distance.