Shear bond strength of orthodontic brackets bonded to high-translucent dental zirconia with different surface treatments: An in vitro study.

PURPOSE: The objective of this study was to compare the shear bond strengths of orthodontic brackets bonded to translucent dental zirconia samples which are anatomically accurate and treated with various surface treatments. METHODS: This in vitro study included 156 samples from 3 brands of high-translucent zirconia split into a control group and 4 surface treatment groups: 9.6% hydrofluoric acid etching, 50-micron aluminium oxide particle air abrasion, and 30-micron tribochemical silica coating (TBS) particle air abrasion with and without silane application. After surface treatment, all groups were primed with a 10-MDP primer and bonded to metal orthodontic brackets. Shear bond strength (SBS) was tested and results were compared between all groups. Data analysis consisted of a balanced two-factor factorial ANOVA, a Shapiro-Wilks test, and a non-parametric permutation test. The significance level was set at 0.05. RESULTS: Among all surface treatments, aluminium oxide particle abrasion produced significantly higher SBS (P≤0.002). Lava™ Plus zirconia samples had significantly higher SBS than Cercon® samples (P<0.0001). TBS surface treatment produced significantly higher SBS on Lava™ Plus samples than it did on the other zirconia brands (P=0.032). CONCLUSIONS: This study indicated that mechanical abrasion using aluminium oxide in combination with a 10-MDP primer creates a higher SBS to high-translucent zirconia than the bond created by tribochemical silica coating. Also, there was no significant difference in ARI regardless of zirconia brand or surface preparation.

An overview of current evaluation methods of postgraduate dental specialty residents.

PURPOSE: A lack of contemporary dental literature exists on evaluating dental residents in postgraduate education, with no standardized criteria or information on technology adoption. This study aims to understand current evaluation methods in dental residency programs and compare them to existing literature. METHODS: A survey with 22 questions was sent to program directors of 749 ADA/CODA (American Dental Association/Commission on Dental Accreditation)-accredited postgraduate dental residencies. The questions focused on evaluation frequency, faculty involvement, submission methods, and electronic software usage. RESULTS: The survey response rate was 30.2% (226 responses). Results show that 98% of program directors are involved in evaluations, but require more support from auxiliary faculty. Evaluations are typically submitted twice or four times a year, with 12% of programs wanting increased frequency. Face-to-face delivery of feedback is considered crucial. While desktop computers are widely used for evaluation submission, 55% of programs utilize mobile devices, which correlates with higher program director satisfaction. The most popular evaluation software includes New Innovations, MEd Hub, and Qualtrics. Overall, 86.96% of program directors are satisfied with current evaluation practices. Areas needing improvement are non-program director faculty involvement, resident response/feedback, and software navigation. CONCLUSION: This study found that a majority of program directors of the postgraduate dental education system are using electronic technology for their resident evaluation systems and are satisfied with their current mechanism of evaluation.

A survey of white spot lesion prevention and resolution in the US dental school curricula.

PURPOSE/OBJECTIVES: White spot lesions (WSLs) are opaque white lesions on smooth tooth surfaces as a result of demineralization. Proven methods of prevention and resolution of these lesions are available yet the incidence rate, especially in orthodontic patients, is still high. Perhaps the way dental schools are educating students on the topic is insufficient. The purpose of this study was to determine if and how predoctoral dental students are taught about the prevention and resolution of WSLs. METHODS: An electronic survey was developed and sent out to each of the 66 accredited dental schools in the United States and Puerto Rico. The survey consisted of 13 questions and inquired about whether the school includes instruction of WSLs in its predoctoral curriculum. If the school indicated instruction WSLs was in the predoctoral curriculum, further questions were asked pertaining to the content and method of the instruction. Demographic data was also gathered from each institution. RESULTS: Twenty-eight of the 66 schools responded for a 42% response rate. Eighty-two percent of schools indicated they were teaching about prevention of WSLs, while 50% indicated they were teaching about resolution, or treatment, of WSLs. The most commonly taught methods were patient education, over-the-counter fluoride mouthrinse, toothpaste, or gel, and high fluoride content toothpaste. CONCLUSION: The majority of responding dental schools are at least including some instruction of WSLs in the predoctoral curriculum. Many of the known prevention and treatment measures available, however, are not routinely taught.

Shear bond strength of adhesive precoated brackets: A comparative in vitro study.

OBJECTIVE: This study compared the shear bond strength of orthodontic precoated brackets from different manufacturers. METHODS: Sixty extracted human premolar teeth were divided into six groups (n=10). The groups were bonded with one of the following brackets: 3M™ Unitek Victory™ Series™ with APC, 3M™ Unitek Clarity™ Advanced Ceramic™ with APC, TP Nu-Edge® NX Cobalt-Chromium and TP In-Vu® ceramic Readi-Base® both with eXact® orthodontic adhesive, 3M™ Unitek Clarity Advanced Ceramic™ and 3M™ Unitek Victory™ Series™ both with Transbond™ XT Adhesive. Each group was tested for shear bond strength using a universal testing machine. Each sample was observed under a dissecting microscope and received an adhesive remnant index (ARI) score. Statistical analysis was performed using Tukey's Standardized Range (HSD) Test to make comparisons among all groups and a Wilcoxon rank-sum test to evaluate for pairwise comparisons between the groups. The P-values<0.05 were considered significant. RESULTS: The ceramic control was not statistically different from the metal control, 3M™ Victory™ APC™, TP In-Vu® ceramic eXact® or TP Nu-EDGE® eXact® in terms of shear bond strength (7.69±1.41MPa, 7.72±1.25MPa, 8.70±1.93MPa, 4.90±1.76MPa, 5.33±0.78MPa, respectively). However, it was statistically different from 3M™ Ceramic APC™ (10.29±2.78MPa). In terms of modulus, there were no statistical differences. TP's Nu-edge® had the lowest average ARI score, but was not statistically different when compared to the other groups. CONCLUSION: 3M™ Unitek's Ceramic APC had a statistically higher SBS than the non-precoated brackets and TP Orthodontics' precoated brackets. However, all SBS were 4.9 MPA or above, which is deemed clinically acceptable in terms of laboratory forces. There was no statistical difference between manufacturing companies or precoated vs. non-precoated modulus and ARI scores.

Direct Comparison Between Intraoral Scanning and Alginate Impressions for Pediatric Patients: An In Vitro Study.

Purpose: To compare the accuracy and efficiency of both alginate and digital impression techniques in a method representative of a clinical setting. By evaluating the difference in fabrication time and accuracy for these techniques, it can be determined if using digital scanning is a viable alternative to alginate impressions to fabricate pediatric dental appliances.
Methods: Both the alginate and digital impressions were taken from the same pediatric typodont study model. The alginate impressions were handled and poured up, per product instructions, and digital impressions were 3D printed. A digital caliper was used to measure different landmarks on both the stone models and 3D printed models, and these measurements were compared to the pediatric typodont to determine accuracy. All steps in the process, including obtaining the impression, fabrication of the model and total time, were recorded to determine the efficiency of both methods.
Results: The alginate models had a significantly higher intercanine distance than the control. Measurements of anterior-posterior (AP) left, AP right, left central, and right central were larger than the control but did not show a significant difference in measurement. The alginate group had a significantly shorter impression time. Model fabrication time between the two groups was similar.
Conclusion: Alginate impressions require less chairside time and the digital technique was shown to be accurate in all measurements. Digital scanning may be a good alternative to alginate impressions for pediatric patients.

The prevalence of developmental dental and eruption anomalies assessed using panoramic radiographs: a retrospective study.

Developmental dental anomalies are a common finding in adolescent populations. The objective of this study was to utilize panoramic radiographs to determine the prevalence of dental anomalies and developmental disturbances in a heterogenous adolescent orthodontic patient population seeking care at a North American orthodontic residency program. A total of 1042 panoramic radiographs of 457 male and 585 female orthodontic patients aged 10 to 18 years were evaluated. Developmental and eruption anomalies were recorded and categorized, and chi-square and Fisher exact tests were used for statistical analysis. The evaluation revealed that 40.88% of patients had at least 1 anomalous finding. The most common finding overall was agenesis (12.00%), followed by deviations in eruption path (9.12%), delayed eruption (7.39%), and impaction (7.29%). There was no difference in the prevalence of having any anomalous finding or the prevalence of any specific category of anomalies based on the sex or Angle classification of the patients. Comparison of developmental dental anomalies in 3 age groups (10 to 12, 13 to 15, or 16 to 18 years) revealed no statistically significant difference in the overall prevalence of anomalous findings. Statistically significant differences for some specific categories of anomalies were explainable by correlating dental development with chronologic age, such as a greater frequency of blocked out teeth and eruption path deviation among patients aged 10 to 12 years. Black patients were found to have a significantly greater prevalence of impactions (P = 0.030), and Asian patients had a significantly greater prevalence of anomalies categorized as "other pathology," which could not be definitively diagnosed by panoramic radiograph alone (P = 0.007).

Quantifying the degree of white spot lesions on enamel caused by different commercial beverages using the Canary Caries Detection System: An in vitro study.

Background. The use of sports and energy drinks has drastically increased in the adolescent population. This population often is in orthodontic treatment, and the use of such drinks with poor oral hygiene promotes the development of white spot lesions (WSLs). Quantifying the degree of the lesion has been limited in the past. The hypothesis was that the Canary Caries Detection System could be used to quantify the degree of WSLs caused by different commercial beverages. Methods. A total of 105 extracted human premolars were divided into seven groups (n=15). Each group was tested in one of six beverages or a phosphate-buffered solution (control). The teeth were exposed to its beverage three times a day for 15 minutes for 28 days. Canary numbers and ambient light and fluorescent photographs were collected at baseline (T0 ) and on days 14 (T1 ) and 28 (T2 ). Results. The paired t test and one-way ANOVA found that T0 to T1 measurements were statistically significant (P<0.0015) and that T0 to T2 measurements were statistically significant (P<0.0001). Visually, the ambient light photographs and fluorescent photographs from T0 to T1 and T1 to T2 correlated with the increase in Canary numbers. Conclusion. This in vitro study revealed a statistically significant increase in the T0 to T1 Canary numbers and a statistically significant increase from T0 to T2 Canary numbers for all the test beverages. Changes in Canary numbers indicated significant changes in mineral density (i.e., demineralization) and development of WSLs on enamel after exposure to sports and energy beverages.

The Effect of Silver Diamine Fluoride on Bond Strength of Three Types of Bulk-Fill Restorative Materials to Dentin.

Purpose: The purpose of this study was to evaluate the effect of 38 percent silver diamine fluoride (SDF) application on the shear bond strength (SBS) of three types of bulk-fill restorative materials to dentin. Methods: Eighty recently extracted deidentified, sound, human premolar teeth were sectioned to expose the mid-coronal dentin. A composite restorative material (ACTIVA™), a giomer (Beautifil®), and a high-viscosity glass ionomer (HVGI) cement (Equia Forte®) were used. The specimens were randomly assigned into eight groups (N equals 10 per group) according to the type of restorative material (ACTIVA™, Beautifil ®, Equia Forte ® with and without the conditioner) and pretreatment with one drop of 38 percent SDF. Both ACTIVA™ and Beautifil ® were bonded to dentin with a universal adhesive (Scotchbond™ Universal). The SBS was measured in a universal testing machine with a 0.5 mm per minute crosshead speed. One-way analysis of variance, Tukey's, and adjusted pairwise comparison tests were used for statistical analysis of data (α equals 0.05). Results: Pretreatment of dentin with SDF did not affect the SBS of the tested bulk-fill materials (P>0.05). The SBS of the ACTIVA™ and Beautifil® groups was similar (P>0.05) and significantly higher than all Equia Forte® groups (P<0.001). Application of conditioner had no significant effect on the SBS values of Equia Forte® (adjusted P>0.01). Conclusions: The application of silver diamine fluoride did not influence the shear bond strength of tested bulk-fill materials to dentin. Prior conditioning did not affect the SBS of the high-viscosity glass ionomer to dentin. The giomer and composite restorative materials showed significantly higher SBS than high-viscosity glass ionomer.

Comparison of Tie Wing Fracture Resistance of Differing Ceramic Brackets.

OBJECTIVE: The aim of this study was to compare the tie wing fracture resistance of 4 different manufacturers' ceramic brackets currently on the market. METHODS: The tie wings of ceramic brackets from 4 manufacturers were tested with 10 samples in each group. The brackets were Ormco Symetri, 3M Clarity, American Radiance Plus, and Dentsply Ovation S. The brackets were mounted and fixed in a universal testing machine. A stainless steel ligature wire was looped around a tie wing and the mean tensile strength was both tested and recorded. RESULTS: There was a significant overall difference in tensile strength among the 4 groups (P < .0001) with the 3M Clarity brackets having the highest MPa. When the groups were compared to each other, they also showed a significant difference in mean tensile strength with the exception being the American Radiance Plus and Ormco Symetri brackets. CONCLUSION: Test results concluded that the 3M Clarity brackets had the highest resistance to tie wing fracture, while the Dentsply Ovation S brackets had the lowest resistance.

A comparison of traditional orthodontic polishing systems with composite polishing systems following orthodontic debonding.

INTRODUCTION: At the completion of treatment, the orthodontic practitioner's goal is to effectively remove all traces of adhesive and return enamel to its initial state. With the advent of new polishing systems being released each year, there may be one product that is superior to others. AIM: The purpose of this study is to determine the efficacy of new polishing systems (in the last 5-10 years) used in general dentistry on enamel surface roughness following debond utilizing profilometery and scanning electron microscopy and compare them to established orthodontic polishing systems results. METHODS: Fifty-two mandibular incisors were randomly assigned to one of five test groups (N = 10) and two incisors (untreated enamel) were used for profilometer and scanning electron microscopy analysis at the end of testing. After bracket removal, the teeth were polished using traditional polishing products (Komet H48L bur, Reliance 'Renew' point) and newer polishing products (Coltene Spiral Composite Plus Polisher, Ultradent Jiffy Composite Polishing Spiral or 3M Sof-Lex™ Diamond Polishing System). The results were evaluated using a profilometer and scanning electron microscopy images. RESULTS: The results of a one-way analysis of variance (ANOVA) determined that the mean change in enamel surface roughness was not statistically different both in the traditional and novel groups. Tukey's Honestly Significant Difference (HSD) test found that there was no statistically significant difference in the change in enamel surface roughness between instrument groups. CONCLUSIONS: There was no statistically significant difference in enamel surface roughness after polishing between traditional orthodontic polishing systems and the selected novel polishing systems. SEM analysis revealed similar findings. This supports previous research suggesting that a wide variety of polishing systems or none at all, may be used to restore enamel smoothness after removal of orthodontic appliances.

Prevalence of Molar-Incisor Hypomineralization Within an Orthodontic Department in the United States.

Purpose: The purpose of this study was to determine the prevalence and severity of molar-incisor hypomineralization (MIH) by examining standard orthodontic intraoral photographs. Methods: A total of 690 patients were evaluated retrospectively for the presence or absence and extent of MIH using standardized assessment criteria. Results: Fourteen percent of all patients examined presented with MIH on at least one tooth. There was no significant difference in the presence of MIH when compared to age, race, or gender. MIH is most commonly presented on maxillary molars and maxillary central incisors as demarcated opacities with less than one-third of the tooth affected. More severe clinical status groups were associated with higher average age and were more commonly seen in molars than incisors. Conclusions: At 14 percent, the prevalence is reflective of the worldwide prevalence previously determined from other studies. MIH most commonly presents in its mildest form; however, older individuals tend to present with more severe forms, indicating that it continues to cause problems as patients age. Future studies should extend to further areas to continue to ascertain the extent and severity of this condition.

Comparison of tensile bond strength of new and rebonded Symetri Clear™ ceramic brackets with Transbond™ XT or BluGloo™, with or without surface treatment: An in vitro study.

OBJECTIVES: This study sought to determine the bond strength of the Symetri Clear™ bracket after rebonding (reused) for a second and third time. MATERIALS AND METHODS: Symetri Clear™ mandibular incisor brackets were bonded to bovine incisors and divided into six experimental groups. Two groups underwent tensile bond strength testing, and the remaining four groups were debonded using the manufacturer's recommended plier. Two groups were rebonded twice following surface preparation with Ortho SoloTM and two groups were rebonded twice without surface preparation. The rebonded brackets also underwent tensile bond strength testing after each rebonding event as well as receiving an Adhesive Remnant Index score. RESULTS: One-way ANOVA found a statistically significant difference in bond strength among the six groups (P<0.0001). Tukey's Studentized Range (HSD, honestly significant difference) Test found significant differences in tensile bond strength of groups which did not undergo surface preparation prior to rebonding. One-way ANOVA found a P-value of 0.2563 and thus no significant difference in ARI among the different groups. CONCLUSIONS: There was no significant difference in the tensile bond strength of Symetri ClearTM brackets initially bonded with either Transbond™ XT or BluGloo™ and no significant difference between the initial tensile bond strength and the first or second rebond tensile bond strength. Rebonding Symetri Clear™ brackets without surface treatment did show significantly reduced tensile bond strength.

In vitro comparison of shear bond strengths of ceramic orthodontic brackets with ceramic crowns using an aluminium oxide air abrasion etchant.

OBJECTIVE: The aim of this study was to determine if there are differences between the shear bond strengths of 3 types of ceramic brackets when bonded to different ceramic substrates using an aluminium oxide air abrasion etchant protocol. MATERIALS AND METHODS: Substrate groups consisting of thirty-six lithium disilicate (e.max® CAD) samples and thirty-six lithium silicate infused with zirconia (CELTRA® DUO) samples were fabricated to replicate the facial surface of a left maxillary central incisor. The surface of all samples was prepared with an aluminium oxide air abrasion etchant protocol. Each substrate group was split into three test groups (n=12). Each test group was bonded using a different brand of ceramic orthodontic bracket. Shear bond strength (SBS) testing was conducted and the mean SBS values for each group were calculated and recorded in MPa. An Adhesive Resin Index (ARI) score was also assigned to each sample to assess the location of bond failure. RESULTS: Mean SBS of the e.max® CAD groups were significantly less than the CELTRA® DUO groups. Symetri brackets showed significantly higher shear bond strengths to both substrates than both of the other brackets tested. ARI scores of the e.max® CAD groups were significantly less than the CELTRA® DUO groups. CONCLUSION: The Symetri bracket was the only bracket that was effective for both substrates (mean SBS>6mPa). The Etch Master protocol does not appear effective for e.max® CAD.

Dental Student and Faculty Perceptions of Uncivil Behavior by Faculty Members in Classroom and Clinic.

Uncivil behavior by a faculty member or student can threaten a classroom environment and make it less conducive to learning. The aim of this study was to explore faculty behaviors that dental faculty and students perceive to be uncivil when exhibited in the classroom and clinic. In 2015, all faculty, administrators, and students at a single academic dental institution were invited to participate in an electronic survey that used a five-point Likert scale for respondents to indicate their agreement that 33 faculty behaviors were uncivil. Response rates were 49% for faculty and 59% for students. Significant differences were found between student and faculty responses on 22 of the 33 behavioral items. None of the three category composite scores differed significantly for students compared to faculty respondents. The category composite scores were not significantly associated with gender, ethnicity, or age for faculty or students. Overall, this study found significant differences between students and faculty about perceived uncivil faculty behaviors, though not for categories of behaviors.

Porcelain surface conditioning protocols and shear bond strength of orthodontic brackets.

AIM: The objective of the present study was to determine which of six bonding protocols yielded a clinically acceptable shear bond strength (SBS) of metal orthodontic brackets to CAD/CAM lithium disilicate porcelain restorations. A secondary aim was to determine which bonding protocol produced the least surface damage at debond. METHODS: Sixty lithium disilicate samples were fabricated to replicate the facial surface of a mandibular first molar using a CEREC CAD/CAM machine. The samples were split into six test groups, each of which received different mechanical/chemical pretreatment protocols to roughen the porcelain surface prior to bonding a molar orthodontic attachment. Shear bond strength testing was conducted using an Instron machine. The mean, maximum, minimal, and standard deviation SBS values for each sample group including an enamel control were calculated. A t-test was used to evaluate the statistical significance between the groups. RESULTS: No significant differences were found in SBS values, with the exception of surface roughening with a green stone prior to HFA and silane treatment. This protocol yielded slightly higher bond strength which was statistically significant. CONCLUSION: Chemical treatment alone with HFA/silane yielded SBS values within an acceptable clinical range to withstand forces applied by orthodontic treatment and potentially eliminates the need to mechanically roughen the ceramic surface.

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.

Enamel surface roughness of preferred debonding and polishing protocols.

OBJECTIVE: This study investigated the surface roughness of enamel after debonding and instrumentation with commonly used methods. METHODS: Part I: a survey was sent to active members of the American Association of Orthodontists to determine popular bonding, debonding, and polishing protocols. Part II: brackets were bonded to the buccal surface of 30 extracted human premolar teeth. After debonding, residual adhesive was removed with 12-, 16-, and 20-fluted titanium carbide burs as based upon the survey results. The teeth were scanned with a surface profilometer for surface roughness. Part III: the teeth were further polished using a Reliance Renew polishing point or a prophy cup with pumice and rescanned for surface roughness. RESULTS: Part I: the majority of respondents used a generic bracket-removing plier to remove fixed appliances (53%) and a high-speed handpiece for adhesive removal (85%). The most popular bur was a 12-fluted carbide bur without water spray. The majority of respondents used pumice paste and/or Reliance Renew points after adhesive removal. Part II: there was a significant difference in enamel surface roughness when 12-, 16-, and 20-fluted carbide burs were compared via surface profilometry. Part III: further polishing with a Reliance Renew point or a prophy cup and pumice did not provide a significantly smoother surface. CONCLUSIONS: The results show large variation in debonding and polishing techniques. Creating a smooth enamel surface is equally possible with 12- or 20-fluted carbide burs. Further polishing with pumice and prophy cup or Renew point does not provide an enamel smoother surface.

Relationship between hand-skill exercises and other admissions criteria and students' performance in dental school.

The aim of this study was to investigate the existence of correlations between dental admissions criteria, including a chalk carving exercise, and students' subsequent academic performance. The retrospective cohort study examined the records of dental students at Louisiana State University Health Science Center School of Dentistry for the years 1998 to 2008. Only those students who could be categorized into the following four groups were included: 1) those who graduated in the top 10% of their class, 2) those who graduated in the bottom 10% of their class, 3) those who repeated a year of dental school, and 4) those who were dismissed or resigned. The study sample consisted of 176 students: 62 in the first group, 62 in the second group, 25 in the third group, and 27 in the fourth group. Data collected were each student's undergraduate grade point average (GPA); chalk carving score; undergraduate biology, chemistry, physics (BCP) GPA; Dental Admission Test (DAT) Academic Average; Perceptual Ability Test (PAT) score of the DAT; total DAT score; grade in preclinical operative dentistry class; grade in morphology and occlusion class; and dental school GPA at graduation. The results showed that only the undergraduate GPA and BCP GPA were significantly higher for students in the top 10% of their class than for other groups. The only positive correlation involving the chalk carving scores was with the preclinical operative dentistry course grade. This study thus found limited correlations between this institution's admissions criteria and its students' success in dental school.

Perceptions of uncivil student behavior in dental education.

Students and faculty members in the health professions classroom are expected to exhibit professional behaviors that are conducive to maintaining a positive learning environment, but there is little published research concerning incivility in the area of dental education. The aim of this study was to evaluate differences in perceptions of incivility between dental faculty and students, between students in different courses of study, and between students in different years of dental study. The study utilized an anonymous electronic survey of all dental faculty and administrators and all dental, dental hygiene, and dental laboratory technology students at a single institution. The survey instrument contained questions concerning perceived uncivil behavior in the classroom and clinical settings. Response rates were 54% for faculty and administrators and ranged from 60% to 97% for students in various years and programs. The results were analyzed based on gender, course of study, year of study, and ethnicity. Significant differences were found regarding perceptions of civil behaviour between faculty and students, male and female students, the year of study, and the course of study. These differences point to the need for further research as well as administrative leadership and faculty development to define guidelines in this area in order to ensure a positive learning environment.

Investigation of force decay in aesthetic, fibre-reinforced composite orthodontic archwires.

BACKGROUND/OBJECTIVES: Because polymer-based materials typically exhibit viscoelastic properties, the objective was to determine if commercially available, aesthetic, fibre-reinforced composite archwires maintain continuous forces without undergoing force decay when deflected continuously. MATERIALS/METHODS: Quasi force decay was evaluated by comparing three-point bending profiles of nickel-titanium (NiTi) and fibre-reinforced composite archwires (BioMers) prior to and after 30 days of continuous deflection of either 1 or 2mm. Paired t-tests or non-parametric signed rank tests were used to statistically compare pre- and post-deflection bending forces. A control group consisting of wires not subject to the 30-day constant deflection was tested to check whether the initial testing altered the second three-point bend test. RESULTS: Significant (P < 0.01) differences in the pre- and post-deflection deactivation force delivery were most evident in the composite 2mm deflection group and all of the NiTi groups. The composite 2mm deflection group failed to deliver consistent forces as the majority of the wires experienced crazing during the 30-day deflection period. The decrease in force delivery in the NiTi groups may be attributed to the small standard deviations. CONCLUSIONS: The composite 1mm deflection group demonstrated that fibre-reinforced composite archwires are able to deliver a consistent force after 30 days of deflection. However, the clinical applicability of these fibre-reinforced composite archwires may be limited as they are unable to sustain deflections of 2mm without experiencing crazing and loss of force delivery. LIMITATIONS: Clinical efficacy of the aesthetic, fibre-reinforced composite orthodontic archwires remains to be observed.