A randomized, controlled, two-month pilot trial of stannous fluoride dentifrice versus sodium fluoride dentifrice after oxalate treatment for dentinal hypersensitivity.

OBJECTIVES: To compare the effects of a stannous fluoride dentifrice and a sodium fluoride dentifrice on dentinal hypersensitivity when used with an oxalate-based regimen combining in-office and at-home treatment. MATERIALS AND METHODS: In this single-center, randomized, controlled, double-blind, pilot clinical trial, 30 subjects were professionally treated at baseline with a 3% oxalate/potassium salt solution on up to two target teeth, then randomized 1:1 to either 0.454% stannous fluoride or 0.243% sodium fluoride overlabeled dentifrice. Both groups were given 6 sensitivity strips (3.14% potassium oxalate gel) and a soft, manual toothbrush. Subjects were permitted to apply strips on up to two teeth, up to three times per tooth, at home as desired throughout the study. Dentinal sensitivity (cold air blast challenge) was assessed at baseline, immediately after post-professional treatment, and at day 60 using the Schiff scale and a Visual Analog Scale (VAS). RESULTS: Immediately after professional oxalate treatment, the overall mean Schiff and VAS score decreased 25.6% and 22.4% from baseline, respectively (p ≤ 0.001 for both). At day 60, further reductions in both mean scores were seen in both groups. There were no significant differences between the groups at day 60. All treatments were well tolerated. CONCLUSIONS: In subjects treated with oxalates for dentinal hypersensitivity, both stannous fluoride and sodium fluoride dentifrices are well tolerated, are feasible for routine use, and do not detract from the desensitizing effects of an in-office and at-home oxalate combination treatment regimen. CLINICAL RELEVANCE: Either stannous fluoride or sodium fluoride dentifrices can be recommended to dentinal hypersensitivity patients who undergo professional oxalate treatment.

Jumpstart Mirror Trainer: A New Device for Teaching Mirror Skills to First-Year Dental Students.

Learning indirect vision with a dental mirror is challenging and can be overwhelming for beginning dental students. The Jumpstart Mirror Trainer is a new device that allows students to become proficient with mirror use before the start of preclinic without requiring in-class practice sessions. The aim of this study, conducted in 2017, was to compare the effectiveness of the Jumpstart Mirror Trainer with the Mirroprep for teaching indirect motor skills. Forty-seven first-year dental students were randomized into three groups to use the Jumpstart Mirror Trainer, Mirroprep, or a control device for 15 minutes a day for ten days. To assess indirect motor skills improvement, students performed a maxillary cavity preparation before and after using their devices. A survey was used to assess students' comfort level with mirror skills and perceived helpfulness of the exercises. Forty students completed the study. The Jumpstart Mirror Trainer activities improved the students' scores significantly more than the Mirroprep activities (p=0.04) and the control device (p=0.006). Students in the Jumpstart Mirror Trainer group rated their device as being significantly more helpful than the control group rated its device in preparing them for the evaluation (p=0.001). There was no statistically significant difference in perceived helpfulness between the Mirroprep group and the control group (p=0.75). These results suggest that the Jumpstart Mirror Trainer may be able to improve students' indirect motor skills without requiring in-class practice sessions and to do so more effectively than other existing methods.

A randomized, controlled comparison of two professional dentin desensitizing agents immediately post-treatment and 2 months post-treatment.

PURPOSE: To compare the desensitizing effects of two different marketed professional dentin hypersensitivity treatments, a 5% sodium fluoride varnish and an oxalic acid/potassium salt solution, in a single-center, randomized, controlled, subject-blind pilot study. METHODS: A total of 22 subjects with dentin hypersensitivity on at least two teeth were recruited from a general dentistry practice and randomized 1:1 to treatment with a 5% sodium fluoride varnish (Acclean Fluoride Varnish) group or a 3% oxalic acid/potassium salt solution (Super Seal Desensitizer). The study population was predominantly female (91%) and Caucasian (77%). The mean age was 46.4 years, with ages ranging from 18-73 years. Dentin hypersensitivity was assessed after an air blast challenge by the examiner (Schiff Index Sensitivity Scale) and by the subject [Visual Analog Scale (VAS)] for each tooth tested. Hypersensitivity was assessed immediately post-treatment and at 2 months post-treatment. RESULTS: For the sodium fluoride varnish group, the mean Schiff score decreased 61% from baseline immediately post-treatment (P= 0.0006) and 41% at Month 2 (P= 0.0069). For the oxalic acid/potassium salt solution group, the mean Schiff score decreased 33% from baseline immediately post-treatment (P= 0.0305) and 29% at Month 2. Similarly, the mean VAS scores in the sodium fluoride varnish group decreased 41% from baseline immediately post-treatment (P= 0.0030) and 34% at Month 2 (P= 0.0275). The mean VAS scores in the oxalic acid/potassium salt solution group decreased 35% from baseline immediately post-treatment (P= 0.0168) and 33% at Month 2 (P= 0.0283). An analysis of covariance found no statistically significant between-group differences in mean Schiff scores or VAS scores immediately post-treatment or at Month 2. Both treatments were well tolerated. There were no reported adverse events in either treatment group. CLINICAL SIGNIFICANCE: Both 5% sodium fluoride varnish and an oxalic acid/potassium salt solution are safe and effective options to treat dentin sensitivity in otherwise healthy adults. The examiner-rated Schiff scores and the patient-rated VAS scores consistently demonstrated a reduction in sensitivity with either treatment, both immediately after professional application and at 2 months post-treatment.

Effect of instruction, light curing unit, and location in the mouth on the energy delivered to simulated restorations.

PURPOSE: To determine the amount of energy (Joules/cm²) delivered by students to simulated restorations in a patient simulator based on the restoration location, the curing light unit used, and before vs. after instruction on how to improve their light curing technique. METHODS: 30 dental students "light cured" two simulated restorations (that were 1-mm deep anterior and 4-mm deep posterior) using three light-curing units (LCUs) : VALO, Bluephase G2, and Optilux 401. A MARC Patient Simulator was used to measure the irradiance (mW/cm²) received by the restorations in real-time to calculate the radiant exposure (J/cm²) delivered during a 20-second exposure. At first, students were asked to use the light curing technique that they had been previously taught. They were then given 5 minutes of additional verbal instructions and a practical demonstration on proper curing technique using the patient simulator. They then light cured the restorations again. Based on a literature review, 16 J/cm² was considered the minimum acceptable radiant exposure. RESULTS: Before receiving instruction using the simulator, some students delivered as little as 4 J/cm² to the restoration. A mixed model test determined that the radiant exposure delivered to the anterior restoration was significantly greater than that delivered to the posterior restoration (Plt; 0.001). Additionally, when the locations were compared for each LCU individually, a paired t-test determined that before the students received the additional instruction, the anterior restoration received a significantly greater radiant exposure than the posterior restoration, for all three LCUs. Further paired t-tests and Wilcoxon signed-rank tests determined that after instruction, the radiant exposure improved significantly at both the anterior and posterior locations, for all three LCUs. The Bluephase G2 and the VALO each individually delivered 45% more radiant exposure than the Optilux 401 (P< 0.001 for both). The Bluephase G2 and VALO lights delivered similar mean radiant exposures (25.4 J/cm² and 25.7 J/cm², respectively). This difference was not significant. Depending on the light unit used, at the posterior location, there was a 24 to a 52% increase in the mean radiant exposure that was delivered after instruction compared to before instruction. CLINICAL SIGNIFICANCE: Prior to using the patient simulator, students and their instructors thought that the students were delivering an adequate amount of energy when light curing. This was not always the case. The location of the restoration, the curing light output, its size and shape and how it is used all affected the amount of energy delivered to a restoration. Dental professionals and educators should be aware that appropriate training can improve the amount of energy delivered, and that restorations in posterior teeth will require longer exposure times than those in anterior teeth.

The Benefit of a Switch: Answer-Changing on Multiple-Choice Exams by First-Year Dental Students.

The aim of this study was to determine if dental students would benefit from changing their initial responses to what they have deemed to be more suitable answers during high-stakes multiple-choice examinations. Students are often advised to stay with their first answers despite evidence from other fields suggesting this is not the best course for obtaining optimal final exam scores. Data were collected for 160 first-year DMD students in fall 2013 for three operative dentistry and four biochemistry exams at Tufts University School of Dental Medicine. As students take all of their exams through ExamSoft, a test-taking software application that tracks and records all changes students make during the exam period, the subjective nature of previous studies on answer changing was eliminated. The results showed that all students changed their answers on a minimum of nine questions over the seven exams, with an average of 26.55 (SD=8.8) questions changed per student. Answers changed from an incorrect to a correct response comprised nearly 65% of total answer changes, while changes from a correct to an incorrect answer encompassed slightly above 10% of answer changes. Nearly all students (99.4%) benefitted from answer-changing with a net gain of at least two correct questions, with only one student not increasing the final score. Overall, the students greatly benefitted from changing their answer choice, suggesting that dental students could be advised to change their answers from their first choice if they identify a better option when taking multiple-choice exams.

Creation and Initial Outcomes of a Selective Four-Year Research Program for Predoctoral Dental Students.

Educators agree that dental students' involvement in research plays an important role in their development and contributes to the future of dental education. However, dental schools are challenged to provide the time and support necessary to nurture their students in undertaking research activities. The aim of this study was to examine student participation in a predoctoral student research program at one U.S. dental school and to track participants' outcomes both before and after introduction of an additional, highly selective research scholarship program. Research participation was recorded for all predoctoral dental students in the graduating classes of 2005-15. The number of years of participation was also tracked for each student who participated in research. The results showed that, since the inception of the research honors scholarship in 2005, there has been a more than threefold increase in the number of dental students participating in research each year. The number of students who do multiple years of research has tripled, and the number of students' poster presentations at national academic meetings has risen tenfold in those ten years. The introduction of a competitive award that recognizes exceptional research by students has added to the research profile of the school and has shown success in encouraging students to become involved in research throughout their four years in dental school.

Clinical Significance of Bis-GMA and HEMA Orthodontic Resins Bonding to Enamel and Ceramic Materials.

The advancement of new ceramic materials for dental crowns has prompted the need for improved methods of bonding orthodontic brackets to these surfaces. Currently, lithium-disilicate is the primary material being used for anterior crowns, while zirconia is the primary material being used in the posterior. The purpose of this study was to compare the shear bond strength of HEMA (Assure® Universal Bonding Resin) and bis-GMA (Assure® PLUS All Surface Bonding Resin) orthodontic bonding resins on enamel, lithium-disilicate, and zirconia materials. Two groups were formed, with three tested surfaces per group (n = 20). The categories included premolars, zirconia rods, and lithium-disilicate rods. Group 1 was treated with Assure, and group 2 was treated with Assure PLUS. Zirconia rods (1 cm x 1 cm x 4 cm) were used to represent zirconia crowns, and IPS e.max CAD rods (1 cm x 1 cm x 2 cm) were used to represent lithium-disilicate crowns. Assure and Assure PLUS bonding agents were applied according to the manufacturer's specifications, and standard edgewise universal premolar brackets were secured using Light Bond™ paste without fluoride. After 24 hours the brackets were sheared with a universal testing machine (Instron® 5566A) and the results were recorded. Data were analyzed using a combination of ANOVA and Tukey tests. A P value of less than .05 was considered statistically significant. Although group 1 and group 2 gave statistically equivalent results, the authors found that the ease of use when applying the group 2 bonding agent made it a safer, superior product within the confines of this study. It did not require a 4-minute hydrofluoric acid-etch and needed half the curing time of the group 1 agent when bonding to ceramic materials.

Biocompatibility study of lithium disilicate and zirconium oxide ceramics for esthetic dental abutments.

PURPOSE: The increasing demand for esthetically pleasing results has contributed to the use of ceramics for dental implant abutments. The aim of this study was to compare the biological response of epithelial tissue cultivated on lithium disilicate (LS2) and zirconium oxide (ZrO2) ceramics. Understanding the relevant physicochemical and mechanical properties of these ceramics will help identify the optimal material for facilitating gingival wound closure. METHODS: Both biomaterials were prepared with 2 different surface treatments: raw and polished. Their physicochemical characteristics were analyzed by contact angle measurements, scanning white-light interferometry, and scanning electron microscopy. An organotypic culture was then performed using a chicken epithelium model to simulate peri-implant soft tissue. We measured the contact angle, hydrophobicity, and roughness of the materials as well as the tissue behavior at their surfaces (cell migration and cell adhesion). RESULTS: The best cell migration was observed on ZrO2 ceramic. Cell adhesion was also drastically lower on the polished ZrO2 ceramic than on both the raw and polished LS2. Evaluating various surface topographies of LS2 showed that increasing surface roughness improved cell adhesion, leading to an increase of up to 13%. CONCLUSIONS: Our results demonstrate that a biomaterial, here LS2, can be modified using simple surface changes in order to finely modulate soft tissue adhesion. Strong adhesion at the abutment associated with weak migration assists in gingival wound healing. On the same material, polishing can reduce cell adhesion without drastically modifying cell migration. A comparison of LS2 and ZrO2 ceramic showed that LS2 was more conducive to creating varying tissue reactions. Our results can help dental surgeons to choose, especially for esthetic implant abutments, the most appropriate biomaterial as well as the most appropriate surface treatment to use in accordance with specific clinical dental applications.

Use of Oxalate Strips in Dentistry: Overall Response and Case Studies With Recent and Longstanding Sensitivity.

Practice-based research was conducted to assess professional in-office treatment of dentin hypersensitivity with a strip-based device as part of a recall visit. The study population came from two sources within the dental practice. The majority were recall patients with evident sensitivity that was observed during routine care, while others were patients with history of dentin hypersensitivity in dental records. Treatment consisted of a 1.5% oxalate gel on a polyethylene strip (Crest® Sensi-Stop™ Strips, Procter and Gamble) that was professionally applied directly to sensitivity sites. Sensitivity was measured clinically and perceptually prior to and immediately after treatment, and again 30 days later. A total of 27 adults received oxalate gel strip treatment, and analysis focused on tooth location (arch and position) to ascertain the feasibility of introducing professional strip treatment as part of routine care. Results demonstrated that patients with cervical dentin hypersensitivity were easy to identify, professional strip application was feasible at different tooth sites across both arches, and treatment resulted in both immediate and durable sensitivity effects over a 1-month period.

Silk electrogel coatings for titanium dental implants.

The aim of this study was to develop biocompatible, biodegradable dental implant coatings capable of withstanding the mechanical stresses imparted during implant placement. Two techniques were developed to deposit uniform silk fibroin protein coatings onto dental implants. Two novel coating techniques were implemented to coat titanium shims, studs, and implants. One technique involved electrodeposition of the silk directly onto the titanium substrates. The second technique consisted of melting electrogels and dispensing the melted gels onto the titanium to form the coatings. Both techniques were tested for coating reproducibility using a stylus profilometer and a dial thickness gauge. The mechanical strength of adhered titanium studs was assessed using a universal mechanical testing machine. Uniform, controllable coatings were obtained from both the electrodeposition and melted electrogel coating techniques, tunable from 35 to 1654 µm thick under the conditions studied, and able to withstand delamination during implantation into implant socket mimics. Mechanical testing revealed that the adhesive strength of electrogel coatings, 0.369 ± 0.09 MPa, rivaled other biologically derived coating systems such as collagen, hydroxyapatite, and chitosan (0.07-4.83 MPa). These novel silk-based techniques offer a unique approach to the deposition of safe, simple, mechanically robust, biocompatible, and degradable implant coatings.

Electrodeposited silk coatings for bone implants.

The aim of this study was to characterize the mechanical properties and drug elution features of silk protein-based electrodeposited dental implant coatings. Silk processing conditions were modified to obtain coatings with a range of mechanical properties on titanium studs. These coatings were assessed for adhesive strength and dissolution, with properties tuned using water vapor annealing or glycerol incorporation to modulate crystalline content. Coating reproducibility was demonstrated over a range of silk concentrations from 1% to 10%. Surface roughness of titanium substrates was altered using industry relevant acid etching and grit blasting, and the effect of surface topography on silk coating adhesion was assessed. Florescent compounds were incorporated into the silk coatings, which were modulated for crystalline content, to achieve four days of sustained release of the compounds. This silk electrogelation technique offers a safe and relatively simple approach to generate mechanically robust, biocompatible, and degradable implant coatings that can also be functionalized with bioactive compounds to modulate the local regenerative tissue environment.

Thermal effects on pulp due to laser and handpiece usage.

OBJECTIVE: The study was designed to compare changes in pulpal temperature during ablation of dental hard tissue while using two established erbium dental laser systems, a new CO2 laser system, and a conventional high-speed handpiece. METHODS: Eighty non-carious human extracted molars were separated into four sample groups of 20 teeth each. Three laser systems were used, respectively, to ablate the occlusal surface of the teeth in three of the groups for 60 seconds each. The high-speed handpiece was used to drill the occlusal surface of the fourth group for 60 seconds. Pulpal temperatures were measured using thermocouples inserted into each tooth's pulpal chamber prior to ablation. RESULTS: None of the average temperature increases approached the threshold of 5.5°C at which pulpal damage begins. On average, the pulpal temperature of teeth ablated with the Waterlase MD system increased the most (3.56°C). The traditional handpiece caused the lowest average temperature increase (1.57°C), followed by the LightWalker DT system (3.20°C) and the Solea CO2 system (3.30°C).

Effects of surface treatments and cement types on the bond strength of porcelain-to-porcelain repair.

PURPOSE: The purpose of this in vitro study was to evaluate the effects of four surface treatments and two resin cements on the repair bond strength of a ceramic primer. MATERIALS AND METHODS: Eighty-eight pairs of disks (10 and 5 mm in diameter, 3 mm thickness) were prepared from heat-pressed feldspar ceramics (GC Initial IQ). After being stored in mucin-artificial saliva for 2 weeks, the 10-mm disks were divided into four surface treatment groups (n = 22) and then treated as follows: (1) no treatment (control); (2) 40% phosphoric acid; (3) 5% hydrofluoric acid + acid neutralizer + 40% phosphoric acid; (4) silica coating (CoJet-sand) + 40% phosphoric acid. The 5-mm disks were treated with 5% hydrofluoric acid + 40% phosphoric acid. The two sizes of porcelain disks, excluding the control group, were primed with Clearfil Ceramic Primer. The specimens in each group were further divided into two subgroups of 11 each, and bonded with Clearfil Esthetic Cement (CEC) or Panavia F 2.0 Cement (PFC). The specimens were stored in distilled water at 37°C for 24 hours, thermocycled for 3000 cycles at 5 to 55°C, and stored at 37°C for an additional 7 days. Shear bond strength (SBS) was measured with a universal testing machine at a 0.5 mm/min crosshead speed until fracture. Statistical analysis of the results was carried out with a two-way ANOVA and Tukey HSD test (α = 0.05). Debonded specimen surfaces were examined under an optical microscope to determine the mode of failure. RESULTS: The statistical analysis showed that the SBS was significantly affected by surface treatment and resin cement (p < 0.05). For treatment groups bonded with CEC, the SBS (MPa) values were (1) 2.64 ± 1.1, (2) 13.31 ± 3.6, (3) 18.88 ± 2.6, (4) 14.27 ± 2.7, while for treatment groups cemented with PFC, the SBS (MPa) values were (1) 3.04 ± 1.1, (2) 16.44 ± 3.3, (3) 20.52 ± 2.2, and (4) 16.24 ± 2.9. All control specimens exhibited adhesive failures, while mixed types of failures were observed in phosphoric acid-treated groups. The other groups revealed mainly cohesive and mixed failures. CONCLUSIONS: Combined surface treatment of etching with hydrofluoric acid and phosphoric acid provides the highest bond strengths to porcelain. Also, PFC exhibited higher SBS than CEC did.

Using dental students' preclinical performance as an indicator of clinical success.

The purpose of this study was to evaluate part of one dental school's predoctoral curriculum by investigating correlations between students' final grades in two preclinical courses and their performance in the related clinical courses. The sample consisted of 301 students at Tufts University School of Dental Medicine who graduated in 2010 and 2011. All final grades used as data were obtained from the Registrar's Office and evaluated anonymously. The average preclinical final grades differed significantly for students in the 2010 (M=84.92, SD=3.35) and 2011 (M=79.67, SD=4.67) classes, as did their average clinical final grades (2010: M=88.38, SD=2.13; 2011: M=87.45, SD=2.06). The data for each class were therefore examined separately. Results showed that the correlation between students' preclinical grades and clinical grades in operative dentistry and fixed prosthodontics was statistically significant (2010: r(2)=0.144, p<0.001; 2011: r(2)=0.261, p<0.001). This finding suggests there may be a positive relationship between preclinical and clinical performance of these students; however, the discrete factors contributing to that relationship were not investigated in this study and require further research.

Soft-tissue alterations following exposure to tooth-whitening agents.

BACKGROUND: Tooth-whitening agents are widely used, either as self-application products or under the supervision of a dentist. These products may be associated with transient gross morphologic changes in oral soft tissues. However, their potential effects on human keratinocytes and fibroblasts in a stratified squamous epithelium have yet to be elucidated. METHODS: In this study, three-dimensional human tissue equivalents are exposed to varying concentrations of tooth-whitening agents for increasing time periods. Tissue alterations are investigated in terms of morphology, proliferation, apoptosis, and protein expression. RESULTS: All whitening agents tested altered tissue morphology, induced proliferation of basal keratinocytes, and caused apoptosis of cells in all epithelial strata. In addition, whitening agents induced alterations in the expression of cytokines that are linked to inflammation. CONCLUSIONS: These results suggest that whitening agents may induce similar changes in vivo and that these products should be used for limited periods of time or under the supervision of a dental professional.

Comparison of the effect of two interdental cleaning devices around implants on the reduction of bleeding: a 30-day randomized clinical trial.

OBJECTIVE: To determine the effectiveness of a water flosser in reducing the bleeding on probing (BOP) index around dental implants as compared to flossing. METHODS AND MATERIALS: Patients with implants were randomly assigned to one of two groups in this examiner-masked, single-center study. The study compared the efficacy of a manual toothbrush paired with either traditional string floss or a water flosser. RESULTS: The primary outcome was the reduction in the incidence of BOP after 30 days. There were no differences in the percent of bleeding sites between the groups at baseline. At 30 days, 18 of the 22 (81.8%) implants in the water flosser group showed a reduction in BOP compared to 6 of the 18 (33.3%) in the floss group (P=0.0018). CONCLUSIONS: These results demonstrate that the water flosser group had statistically significantly greater bleeding reduction than the string floss group. The authors concluded that water flossing may be a useful adjuvant for implant hygiene maintenance.

Comprehensive analysis of aerobic and anaerobic bacteria found on dental bib clips.

Multiple-use dental bib clips are considered to present relatively low risks for transmitting infections and, thus, are thought to only require disinfection between patient visits. This study was designed to: 1) determine the presence and composition of bacterial contaminants on reusable rubber-faced metal bib clips after dental treatment at the hygiene clinic at Tufts University School of Dental Medicine and 2) evaluate the effectiveness of the disinfection for this clip type. Aerobic and anaerobic bacterial contaminant loads on the surfaces of the clips were investigated immediately after hygiene treatments were rendered and again after clips were disinfected. The species and strains of bacterial isolates were identified using 16S rDNA sequencing and Human Oral Microbe Identification Microarray analyses. The results demonstrated that although the use of disinfection proved to be significantly effective, some clips retained at least one bacterium on their surfaces after disinfection. Although the bacterial species present on disinfected clips were typical skin or environmental isolates, some were oral in origin. In the study's settings, bacterial presence on the clips did not indicate an infectious disease problem. The different bacterial loads on clips suggest that cross-contamination risks may not be the same for all clinics, and that this difference may be related to the type of treatments and services performed.