Effect of Various Toothpaste Tablets on Gloss and Surface Roughness of Resin-based Composite Materials

OBJECTIVES

To evaluate the effect of various toothpaste tablets on gloss and surface roughness of resin-based composite.

METHODS AND MATERIALS

Sixty-four resin-based composite specimens were divided into four groups of 16 specimens each. Gloss and roughness were measured before and after simulated brushing with three types of toothpaste tablets and one conventional toothpaste: CT: Chewtab Toothpaste Tablets; AT: Anticavity Toothpaste Tablets; HC: Charcoal Toothpaste Tablets; CP: Cavity Protection toothpaste. The Kruskal- Wallis procedure was performed to compare the differences by groups. Post-hoc comparisons were conducted with Bonferroni corrections (α=0.05).

RESULTS

There was a significant drop in gloss for all groups. CT and AT maintained the highest gloss with means of 81.6 GU and 74.1 GU, respectively. The lowest gloss of 24.5 GU was observed for HC. There was a significant increase in roughness for all groups except for CT. CT had the lowest roughness with a mean of 0.034 μm, while HC had the highest roughness with a mean of 0.074 μm. There was a significant correlation between post-brushing gloss and post-brushing roughness (p<0.001, r=-0.884).

CONCLUSION

Chewtab Toothpaste Tablets had the least effect on gloss and roughness, while Charcoal Toothpaste Tablets had the most negative effect on the surface properties of resin-based composites.

Evaluating a method of creating artificial caries in typodont teeth for teaching Class III cavity preparations

OBJECTIVES

The purpose of the study was to report a step-by-step process of creating artificial caries typodont teeth and to determine the perception and efficacy of their use in preclinical operative training.

METHODS

Artificial caries material comprised of commercially available hide glue and chocolate powder for more realistic coloring was embedded into the distolingual of #9 ModuPRO plastic typodont teeth. First-year dental students having no clinical experience in excavating Class III cavity preparations were divided into two groups. Group BA prepared conventional typodont teeth (CTT) first, then artificial caries typodont teeth. Group AB prepared the ACT first, then CTT. The preps were scored employing a rubric used in the operative dentistry course class. A feedback questionnaire was conducted to rate students' satisfaction regarding the use of ACT and CTT. The Mann-Whitney U-test was used to compare the scores between groups ACT-CTT and CTT-ACT and the Chi-Square test was used to evaluate the positive and negative questionnaire responses.

RESULTS

The two groups showed no significant difference in grades and no significant changes in their scores regardless of which order they prepped the teeth (P > 0.05). The questionnaire heavily favored the use of artificial caries typodont teeth (P < 0.05).

CONCLUSIONS

The artificial caries typodont teeth protocol described in this study was feasible when implemented at the preclinical laboratory instruction level with positive questionnaire feedback from dental students.

Impact of Dental Institutions' Values on Students' Intent to Practice in Underserved Communities: A Cross-sectional Study

AIM

To evaluate how an institution's values can impact students' intent to practice in underserved areas.

MATERIALS AND METHODS

The values of 71 accredited dental schools in the United States were searched and tabulated. The American Dental Education Association (ADEA) survey results were used to tabulate the desire to serve the underserved population before entering dental school and upon graduation. Additionally, responses on the total amount of educational debt on graduation was compiled for LLUSD and all other dental schools. Fisher's exact test was performed to compare the difference between the two cohorts and Wilcoxon test was used to assess difference within the groups. Tests were conducted at an alpha level of 0.05 with SAS v 9.1.3 (SAS Institute, Cary, NC, USA).

RESULTS

The top five values of US dental institutions based on frequency were excellence, diversity/inclusion, integrity, innovation, and respect. There was no statistically significant difference between LLUSD and all other dental schools in their desire to serve the underserved community upon graduation (p > 0.05, in all instances). Overall, there was a trend that upon graduation, the desire to serve the underserved had less impact on students' decision-making on their career choices. This drop in the desire to serve the underserved was statistically significant within both cohorts in the year 2021 (p < 0.001).

CONCLUSIONS

Dental institutions should focus on better understanding of how their values impact their students' career choices so that they can develop strategies to better align their values with the mission of addressing the dentist shortage in underserved areas.

CLINICAL SIGNIFICANCE

Dental institutions' values play a major role in impacting students' career choices upon graduation and should be assessed using metrics that are measurable.

A comparison of toothpaste tablets and a sodium fluoride dentifrice for the control of supragingival plaque and gingivitis: A 2-week randomized controlled trial

PURPOSE

To compare toothpaste tablets containing 0.243% sodium fluoride and a conventional sodium fluoride dentifrice for gingivitis and plaque control over a 2-week period.

METHODS

Forty adult participants were randomized into two groups: Toothpaste tablets (Colgate Anywhere Travel Toothpaste Tablets) and conventional dentifrice (Colgate Cavity Protection). A blinded examiner measured the gingival and plaque index at baseline and after 2 weeks. A questionnaire was distributed at the end to determine overall satisfaction of the product used. Statistical analyses were performed separately for the gingival index and plaque index scores. Comparisons of the two treatment groups with respect to baseline and 2-week gingival index and plaque index scores were performed using Mann-Whitney U-test. Within-treatment comparisons of the gingival index and plaque index scores obtained at the 2-week examinations versus baseline were performed using Wilcoxon test.

RESULTS

Both groups had statistically significant improvements in plaque control at the 2-week visit (P< 0.05). There was no statistically significant difference between groups for gingival and plaque index at the 2-week visit (P> 0.05). Overall satisfaction for both products were positive while perception on "texture/foaminess" was more negative for toothpaste tablets (P= 0.001). The results showed that toothpaste tablets' short-term performance on gingivitis and plaque control was equivalent to conventional dentifrice while the " texture/foaminess" of toothpaste tablets was found to be less appealing.

CLINICAL SIGNIFICANCE

Toothpaste tablets are a relatively new form of toothpaste that can be a viable alternative to conventional dentifrice with the added benefit of an eco-friendly way of maintaining oral hygiene.

Effect of toothpaste tablets on gloss and surface roughness of resin-based composite materials

PURPOSE

To evaluate the effects of toothpaste tablets on the gloss and surface roughness of resin-based composite materials and determine the relationship between gloss and roughness.

METHODS

Rectangular jigs were designed and printed. Wells (2 mm deep x 7 mm diameter) were filled with Filtek Supreme Ultra A2B, light-cured and polished. A small-area glossmeter was used for gloss (GU) measurements and a profilometer for roughness measurements (Ra) at baseline and after challenge with each toothpaste. An automated tooth-brushing machine was set at 120 strokes/minute for a total of 10,000 strokes to evaluate four test groups with 16 specimens in each group. NC: Brushing with distilled water; TABS: Colgate Anywhere Travel Tooth Tabs; CP: Colgate Cavity Protection Toothpaste and AW: Colgate Whitening Advanced Toothpaste. Kruskal-Wallis test was used to test the difference in gloss and surface roughness among the groups and Pearson correlation was used to compare the relationship between gloss and roughness.

RESULTS

There was no statistically significant difference in gloss and roughness among the four groups at baseline. At post-brushing, there was a statistically significant difference among the groups (P< 0.001) with increased roughness and decreased gloss for CP and AW when compared to TABS. There was a statistically significant correlation between post-brushing roughness and post-brushing gloss (P< 0.001, rho: -0.815). Thus, the higher the surface roughness the lower the gloss.

CLINICAL SIGNIFICANCE

Toothpaste tablets retain better gloss and roughness of resin-based composite materials when compared to conventional toothpastes.

Assessing Adherence to Provider's Recommendations in Caries Risk Assessment and Management: A Retrospective Data Review

AIM

To evaluate the distribution of caries risk category of patients at a dental institution and determine adherence to providers' recommendations.

MATERIALS AND METHODS

A cross-sectional retrospective review of 1,235 patients records that included data collection on demographics, the sum of the number of decayed, missing due to caries, and filled teeth in the permanent teeth (DMFT), presence of frequent snacking, stimulated salivary flow rate, stimulated saliva pH, saliva buffering capacity, biofilm activity, caries risk category, anti-caries prescription accept/decline, and change in the caries risk category. Statistical analysis was carried out through Pearson's Chi-squared test and linear model ANOVA with a significance level of 0.05.

RESULTS

Pearson's Chi-squared test showed a statistically significant difference in frequency by risk category (p < 0.001) indicating that patients were skewed toward high and extreme caries risk. Linear model ANOVA showed that higher risk categories were associated with lower salivary flow rates (p = 0.010) and higher biofilm activity (p < 0.001). About, 1 out of 3 patients were reported to have frequent snacking (N = 391, 32%). Frequent snacking patients were more likely to present with higher caries risk assessment (p < 0.001), younger age (p < 0.001), and female (p < 0.001). Despite recommendations from the dental student provider, only 27% accepted the anti-cavity prescriptions while 61% declined the recommendation.

CONCLUSION

Distribution of caries risk category is not evenly distributed, but rather skewed toward high and extreme caries risk levels. Despite the identified risks, there is low adherence to the recommendations provided by healthcare providers. The results underscore the necessity for targeted interventions and initiatives aimed at fostering behavioral changes to enhance oral health outcomes.

CLINICAL SIGNIFICANCE

There is a high need for targeted interventions and initiatives that promote behavioral changes to enhance oral health outcomes.

Dental Students’ Knowledge, Attitude, and Confidence toward Evidence-based Dentistry: A 5-year Retrospective Study

AIM

The purpose was to assess dental students' knowledge, attitude, and confidence toward evidence-based dentistry in five graduating Doctor of Dental Surgery (DDS) classes.

MATERIALS AND METHODS

All dental students (class of 2019, 2020, 2021, 2022, and 2023) enrolled in the D3 research design course were required to take a pre-Knowledge, Attitude, and Confidence in Evidence-based Dentistry (KACE) survey. On completion of the 11-week course, a post-KACE survey was distributed to compare the differences in the three domains of evidence-based dentistry (EBD). For the knowledge domain, the responses from the 10 questions were converted to either correct (1) or wrong (0) so that the compiled scores could range from 0 to 10. The attitudes and confidence domains used a five-point Likert scale. The compiled attitude score was a sum of the responses from 10 questions yielding a range from 10 to 50. For confidence, the compiled score ranged from 6 to 30.

RESULTS

The mean knowledge scores of all classes together before and after training were 2.7 and 4.4, respectively. Overall, there was a statistically significant difference between pre- and post-knowledge indicating an improvement in knowledge associated with the training (p < 0.001). The mean attitudes of all classes together before and after the training were 35.3 and 37.2, respectively. Overall, there was a statistically significant improvement in attitude (p < 0.001). The values of mean confidence of all classes together before and after the training were 15.3 and 19.5, respectively. Overall, there was a statistically significant improvement in confidence (p < 0.001).

CONCLUSIONS

A dental curriculum emphasizing Evidence-based practice (EBD) resulted in increased knowledge acquisition, improved attitude, and confidence toward EBD of dental students.

CLINICAL SIGNIFICANCE

Educational initiatives emphasizing evidence-based dentistry increase students' knowledge acquisition, improved attitude, and confidence toward EBD that may also translate to active implementation of EBD in their future practices.

Gold Nanostar Characterization by Nanoparticle Tracking Analysis

We demonstrate the application of nanoparticle tracking analysis (NTA) for the quantitative characterization of gold nanostars (GNSs). GNSs were synthesized by the seed-mediated growth method using triblock copolymer (TBP) gold nanoparticles (GNPs). These GNPs (≈ 10 nm) were synthesized from Au³⁺ (≈ 1 mM) in aqueous F127 (w/v 5%) containing the co-reductant ascorbic acid (≈ 2 mM). The GNS tip-to-core aspect ratio (AR) decreased when higher concentrations of GNPs were added to the growth solution. The AR dependency of GNSs on Au³⁺/Au(seed) concentration ratio implies that growth is partly under kinetic control. NTA measured GNS sizes, concentrations, and relative scattering intensities. Molar absorption coefficients ∼ 10⁹-10¹⁰ M^-1 cm^-1 (ε_400 nm) for each batch of GNSs were determined using the combination of extinction spectra and NTA concentrations for heterogeneous samples. NTA in combination with UV-vis was used to derive the linear relationships: (1) hydrodynamic size versus localized surface plasmon peak maxima; (2) ε_400 nm versus localized surface plasmon peak maxima; (3) ε_400 nm versus hydrodynamic size. NTA for quantitative characterization of anisotropic nanoparticles could lead to future applications, including heterogeneous colloidal catalysis.

A MicroCT Study on Mineral Change over Time Associated with Demineralisation in Primary Teeth

OBJECTIVE

To evaluate the change in demineralisation depth (DD)and mineral density (MD) over time in primary teeth exposed to a demineralisation protocol with microcomputed tomography (microCT).

METHODS

Caries lesions were artificially induced on the labial surfaces of 9 primary incisors by way of a demineralisation protocol using 0.1 M lactic acid with 10% methylcellulose gel for 7 and 14 days. The specimens were scanned with microCT and CTAn software (Bruker, Billerica, MA, USA) was used to analyse the changes in DD and MD. Statistical analyses were performed using SPSS software (IBM, Armonk, NY, USA). Repeated analysis of variance (ANOVA) test and Pearson bivariate correlation were used and the level of significance was set at P < 0.05.

RESULTS

The DD ranged from 0.00 to 0.99 μm (mean ± standard deviation [SD] 0.70 ± 0.43 μm) at baseline, 11.18 to 29.5 μm (18.15 ± 5.23 μm) at 7 days and 18.00 to 55.30 μm (34.20 ± 8.70 μm) at 14 days. The MD for all specimens (n = 9) ranged from 1.48 to 1.76 g/cm3 (1.65 ± 0.08 g/cm3) at baseline, from 1.47 to 1.74 g/cm3 (1.62 ± 0.08 g/cm3) at 7 days demineralisation and 1.33 to 1.72 g/cm3 (1.54 ± 0.13 g/cm3) at 14 days. There were statistically significant differences in DD (P < 0.001) and MD (P = 0.016) between different durations of demineralisation.

CONCLUSION

DD and MD change with time after being exposed to demineralising solution. MicroCT is a nondestructive method that allows repeated MD evaluations of the same sample.

Tooth Color Change and Erosion: Hydrogen Peroxide Versus Non-peroxide Whitening Strips

AIM

The study evaluated the efficacy and potential erosion of non-peroxide strips compared to hydrogen peroxide (HP) whitening strips (WSs).

METHODS

Color evaluation samples (N=64) were distributed into four groups and treated according to manufacturer's directions. NC: Negative control treated with water; BT: Non-peroxide Brilliant Dissolving Strips; FM: Non-peroxide Fancymay Teeth WSs; WS: Crest 3D Brilliance HP White Strips. A contact-type spectrophotometer was used to measure color at baseline (T1), 1-day posttreatment (T2), and 1-week posttreatment (T3). Teeth were cut to a rectangular block for micro-CT erosion assessment. The samples (N=30) were divided into five groups. In addition to the four groups for color assessment, a positive control (PC) treated with 0.25% citric acid was added. The samples were scanned, reconstructed, and measured for erosion depth using a micro-CT analysis program software. Kruskal-Wallis test was used to determine differences in color change and erosion depth among the groups. Tests of hypotheses were two-sided with an alpha level of 0.05.

RESULTS

The mean ΔE*ab at 1-day/1-week posttreatment were 2.4/2.5, 2.8/2.9, 2.8/3.2, and 8.6/11.0 for NC, BT, FM, and WS, respectively. There was a statistically significant difference for ΔE*ab at 1-day and 1-week posttreatment (p<0.001). Group WS had the highest color change, while the other three groups did not differ from each other (p>0.05). Mean erosion depths in microns were 0.52, 0.58, 0.42, 0.49, and 29.55 for NC, BT, FM, WS, and PC, respectively. There was a statistically significant difference among the groups (p=0.004). Group PC had the greatest erosion, while the other groups had negligible erosion that did not differ from each other (p>0.05).

CONCLUSION

Peroxide WSs had superior whitening efficacy compared to non-peroxide strips. None of the tested products compromised tooth structure integrity through enamel erosion.

The Outcome of a New Teledentistry Initiative in Response to the COVID-19 Pandemic: A Cross-sectional Study

AIM

The purpose of this study was to assess the overall satisfaction of a new learning experience and evaluate the outcome of LLUSD's educational teledentistry initiative through a survey based on Kirkpatrick's multidimensional model of training evaluation.

MATERIALS AND METHODS

An IRB application was approved (#5210385) for a cross-sectional study that included Loma Linda University School of Dentistry (LLUSD) dental students of the class of 2022 and 2023. The 9-question survey consisted of three sections. The first section included demographic questions on gender and the graduating class. The second section was related to perceived teaching effectiveness, attitude, behavior, and significance. The third section included an open-ended question. The survey was distributed by three student investigators. Descriptive statistics were calculated, and categorical variables were compared using the Chi-squared test (χ² test).

RESULTS

The perceived teaching effectiveness of the newly implemented educational initiative was high for increasing the ability to communicate with patients and for screening and identifying the need for referrals. A majority of students believed that teledentistry is an important means to improve patients' access to dental care and that the School has been providing a good educational environment in providing teledentistry sessions to patients. There were no significant differences in the frequencies of positive and negative responses to all questions (N = 6) by gender and by class (p >0.05, in all instances).

CONCLUSIONS

Teledentistry eVisits allowed the continuation of patient contact and initial assimilation of patient information. There is potential for this educational initiative to be more actively and comprehensively implemented in the future.

CLINICAL SIGNIFICANCE

New educational initiatives allow the continuation of patient contact that will ensure that students will graduate as competent oral health care providers despite challenges imposed by the pandemic.

Impact of COVID-19 on Teaching the Tooth Morphology Course to the New Generation of Learners: A Cross-sectional Study

AIM

The purpose of the study was two-fold. First, to evaluate students' learning style and relate it to their academic performance. Second, to highlight changes implemented in the tooth morphology (TOMO) course as a response to the coronavirus disease-2019 (COVID-19) pandemic.

MATERIALS AND METHODS

The study was performed during 2021-2022 with 101 dental students. Didactic lectures were delivered online and students challenged with nine quizzes and one final examination. Didactic score was calculated by averaging the scores of quizzes and the final exam. Lab score was a combination of five lab projects and the final competency. At course completion, students received a survey on their learning style and how they would like to receive feedback. Kruskal-Wallis test was used to assess differences in didactic and lab scores among groups.

RESULTS

Many students perceived themselves as visual learners (39%) followed by kinesthetic (24%), aural (19%), and reader (18%). There was no difference among learning style groups in performance of didactic (p = 0.340) and lab scores (p = 0.845). Students preferred that the instructor talks them through the questions for feedback on quizzes (41%) while they preferred demonstrations when receiving feedback on their wax-ups (51%). Most students (75%) preferred a TOMO teacher that uses demonstrations. 2020-2021 marked the year of the pandemic where all lectures were delivered online and waxing projects were performed at-home. A postpandemic transformation occurred during 2021-2022, reverting to conventional in-person lab sessions while keeping online didactic lectures.

CONCLUSION

We conclude that TOMO should be delivered by using various teaching styles rather than focusing on a single method while providing more demonstrations.

CLINICAL SIGNIFICANCE

Teaching tooth morphology to the new generation type of learners efficiently will affect the clinical work of dental graduates.

Laboratory model to evaluate efficacy of an experimental titanium oxide nanofibers bleaching agent

Objectives

This study aimed to use a laboratory model to evaluate the efficacy of an experimental bleaching agent.

Materials and Methods

The model used human extracted molars that were treated and measured for bleaching efficacy. Teeth (n = 50) were distributed into 5 groups: Negative control (NC): immersion in water for 8 hours; Nanofibers (NFs): Experimental titanium dioxide nanofibers with stirring and light activation for 8 hours; Whitestrips (WS): Crest 3D White Glamorous White Whitestrips, 2 applications daily for 30 minutes, 14 days; 1% hydrogen peroxide (HP) standard: 1% hydrogen peroxide for 8 hours; and 30% HP standard: 30% hydrogen peroxide for 8 hours. Instrumental measurements were performed using a spectrophotometer. Results were recorded at baseline, 1-day post-bleaching, and 1-week post-bleaching. Kruskal-Wallis procedure was used to determine differences in color change. Pearson correlation was used to evaluate the relationship between visual and instrumental measurements. Tests of hypotheses were 2-sided with alpha = 0.05.

Results

There was no significant difference in color parameters (L1, a1, b1, and shade guide units [SGU]) at baseline (p > 0.05). There was a significant difference among the groups for overall color change (ΔE*ab) and change in shade guide units (ΔSGU) at 1-day and 1-week post-bleaching (p < 0.05). The higher the HP concentration, the higher the color change as expressed in ΔSGU and ΔE*ab. The negative control exceeded the perceptibility threshold of ΔE* = 1.2 regardless of time point. NFs showed a decrease in chroma, but were not statistically different compared to the negative control.

Conclusions

The laboratory model was successful in screening an experimental bleaching agent.

Effect of charcoal dentifrices on tooth whitening and enamel surface roughness

PURPOSE

To evaluate tooth color change and surface roughness after the use of charcoal dentifrices.

METHODS

Bovine teeth (n= 64) used for color measurements were stained in tea solution and embedded in acrylic resin. Specimens were randomized into four groups of 16 specimens each. Cavity Protection (Colgate-Palmolive) was the negative control. Whitening dentifrices used were Black is White (Curaden AG); and My Magic Mud (Carbon and Clay Company) containing activated charcoal and Optic White (Colgate-Palmolive) containing hydrogen peroxide. Instrumental color measurements were performed at baseline, 1-week post-brushing, 30-day post-brushing, and 1-month follow-up. Another set of bovine teeth (n= 64) used for roughness measurements were embedded in acrylic resin and the surface ground flat. The experimental groups and brushing protocol were the same as for the color evaluation part. Surface roughness was measured with a contact type profilometer at baseline and after the last brushing session. Kruskal-Wallis procedure tested changes in color and surface roughness among the different groups. All post-hoc comparisons were conducted with Bonferroni corrections. Tests of hypotheses were two-sided with an alpha level at 0.05.

RESULTS

Overall color change was not significantly different among groups at 1-week post-brushing and at 1-month follow-up. However, the hydrogen peroxide group had a significantly higher reduction in chroma in the yellow-blue axis when compared to negative control group at 30-day post-brushing and 1-month follow-up (P< 0.05). There was no significant difference in roughness among the groups at baseline (P= 0.2973) and post treatment (P= 0.8169).

CLINICAL SIGNIFICANCE

The use of charcoal dentifrices did not have the claimed whitening effect but did not increase enamel surface roughness.

Micro computed tomography analysis of abrasivity of toothpaste tablets compared to conventional toothpaste

PURPOSE

To evaluate with microCT dentin and enamel abrasion depth caused by toothpaste tablets when compared to conventional toothpastes.

METHODS

Dentin (N= 64) and enamel blocks (N=64) were randomized into four experimental groups of 16 specimens each for dentin and enamel. CP: Colgate Cavity Protection, served as the low abrasive toothpaste; AW: Colgate Total Advanced Whitening was used to represent a highly abrasive toothpaste. Two different types of toothpaste tablets were used. DT: Denttabs and BT: Bite tabs. To prepare the slurries, 40 mL of water was added to 25 g of each toothpaste and 4.4 g of each toothpaste tab. Blocks were brushed for a total of 10,000 and 40,000 strokes for dentin and enamel, respectively following ISO standard 11609. On completion of brushing, specimens were scanned with a microCT system. Tomographic 3D reconstruction followed by abrasion depths measurements were performed. Kruskal-Wallis procedure tested abrasion depths among the different groups. Tests of hypotheses were two-sided with an alpha level at 0.05.

RESULTS

There was a statistically significant difference in dentin abrasion depth among the groups (P< 0.001). The mean dentin/enamel abrasion depths in microns were 25.3/4.4, 36.8/4.4, 66.8/3.0, and 230.3/15.5 for DT, BT, CP, and AW respectively. Dentin and enamel abrasion depth of AW was the highest and was different from all other groups after multiple comparisons (P< 0.05).

CLINICAL SIGNIFICANCE

Dentin abrasivity of toothpaste tabs is negligible as determined with microCT.

Oral health knowledge and oral health related quality of life of older adults

OBJECTIVE

To assess the relationship between oral health knowledge and oral health related quality of life among older adults with different ethnicities living in San Bernardino County, California. There is a gap in oral health knowledge (OHK) and how it relates to perceived oral health related quality of life. Thus, there is a need to assess OHK as a component of oral health literacy and identify areas in which knowledge gaps exit to develop educational strategies that address the need of the elderly population.

MATERIALS AND METHODS

The study was a cross-sectional study that included adults 65 years and older using a validated "Comprehensive Measure of Oral Health Knowledge" (CMOHK) and an "Oral Health Profile Index" (OHIP-14). Odds ratios were conducted to determine the factors associated with OHK.

RESULTS

Mean OHK score were 16.8, 14.6, and 8.9 for Caucasian, Asian, and Hispanics, respectively. "Poor" OHK was significantly associated with participants over the age of 75 years (OR = 1.9; 95% CI: 1.15-3.16), high school education or less (OR = 10.8; 95% CI: 5.92-19.84), minority ethnicity (OR = 7.3; 95% CI: 4.27-12.61), income less than $25,000 (OR = 10.7; 95% CI: 5.92-19.26), and reading ability less than "Excellent" (OR = 7.27; 95% CI: 4.35-12.14). Mean OHIP-Severity scores were 7.4, 12.5, and 24.4 for Caucasian, Asian, and Hispanics, respectively. Respondents with Poor OHK were 5.17 times more likely to be identified with high levels of severity (Severity >10).

CONCLUSION

It is imperative to develop communication strategies to inform older adults on oral health knowledge that provide equal opportunities for all ethnicities.

Dental and Dental Hygiene Students' Knowledge and Perception on Fluoride Use in Dentistry

AIM

The 75th anniversary of community water fluoridation in the United States was celebrated in 2020. However, there are studies that stimulate polarized discussion over the use of fluoride in dentistry. The purpose of this study was to evaluate dental and dental hygiene students' knowledge and perception of fluoride use in dentistry.

MATERIALS AND METHODS

A survey was conducted to gauge participant's knowledge and perception of fluoride and their opinion on the need for developing viable alternatives to fluoride. An Institutional Review Board (IRB# 5190496) application was filed and approved. A hard copy survey was distributed to all student classes at Loma Linda University School of Dentistry (U.S.) between January 13, 2020, and February 5, 2020. Descriptive data were compiled and analyzed. Knowledge-based questions were compared using Kruskal-Wallis procedure to evaluate correct percentage among different classes. Perception questions were analyzed using a Likert scale and also a Chi-squared test. All tests were two-sided with α at 0.05.

RESULTS

Out of 482 students, 282 students responded (58.5%). The mean of correct responses for knowledge ranged from 49 to 69%. There was a statistically significant difference among the classes. Overall the perception of the use of fluoride in dentistry was positive, and it changed with exposure to lectures on fluoride over the years.

CONCLUSION

There was a correlation between knowledge and the perception of the use of fluoride in dentistry, indicating the importance of adequate delivery of didactic teaching on knowledge of fluoride to dental and dental hygiene students.

CLINICAL SIGNIFICANCE

The oral healthcare provider plays a pivotal role in communicating pertinent information on the benefits of fluoride in preventing dental caries to the general public, prompting adequate delivery of didactic teaching on this topic in dental education.

Measurement of erosion depth using microcomputed tomography and light microscopy

Tooth-erosion is the surface loss of dental hard tissue mostly associated with an acid attack. The aim was to compare dentin and enamel erosion depth measurements using micro-computed tomography (microCT) and light microscopy (LM). Enamel/dentin blocks were prepared from caries-free human molar-teeth (N = 12). Teeth were sectioned to a rectangular shape of 4 × 4 × 6 mm. Specimens were treated with water (NC) or 1.0% citric-acid solution (PC). After treatment, specimens were scanned with micro-computed tomography. On completion, specimens were sectioned and observed under a light-microscope. Lesion depth was observed with 10× magnification and images transferred to Simpleware software. Vertical distance from lesion surface to bottom was measured. Pearson correlation test was used to evaluate correlation and Wilcoxon Signed Rank test to evaluate differences in the two-analysis methods. Mean enamel erosion depth was 0.63 and 38.38 μm (microCT) and 0.54 and 39.43 μm (LM) for NC and PC, respectively. Dentin erosion depth was 0.72 and 48.05 μm (microCT) and 0.56 and 49.92 μm (LM) for NC and PC, respectively. There was a significant correlation between the two-analysis methods (r = 0.998; p < .001). No statistically significant difference in results were obtained when microCT and LM were compared (p = .584). This results obtained from the current study suggested that erosion depth measurements made using microCT and LM yielded comparable results. The microCT method is preferred if the conservation of specimens is desired.

Potential Penetration of CTAB- and MUDA-coated Gold Nanorods into Tooth Enamel

AIM

Gold nanorods (GNRs) have gained interest as a promising carrier for antibiotics. Gold nanorods may reduce the development of antimicrobial resistance in certain microbial species. Although applications of GNRs to mitigate oral biofilms are under development, their use in the oral cavity may have adverse effects. The aim of this study was to evaluate the potential penetration of GNRs into the tooth enamel structure using confocal laser scanning microscopy (CLSM) and scanning transmission electron microscopy (STEM).

MATERIALS AND METHODS

Our approach was to synthesize GNRs with cationic [cetyltrimethylammoniumbromide (CTAB)] and anionic [11-mercaptoundecanoic acid (MUDA)] surface coatings. We hypothesized that penetration would be surface coating dependent.

RESULTS

Regardless of the chemical modification of the GNRs of size ∼20 nm × 8 nm, exposure of these materials did not result in superficial penetration into the enamel.

CONCLUSION

Within the limitations of this study, it is concluded that the use of CLSM and STEM is a feasible approach to investigate the penetration of nanomaterials into the tooth structure.

CLINICAL SIGNIFICANCE

Exposure of the enamel with chemically modified GNRs of size ∼20 nm × 8 nm will not result in superficial penetration into the enamel.

Systematic review of in vitro studies evaluating tooth bleaching efficacy

PURPOSE

To review and assess the literature on in vitro studies evaluating tooth bleaching efficacy considering the use of a negative control, type of tooth substrate, storage medium, color evaluation methods, and evaluation time points.

METHODS

The following databases were searched: PubMed (MEDLINE), Web of Science. Search used Medical Subject Headings (MeSH) in PubMed in addition to free text. The following limits were applied: English, articles published between January 1989 and October 2017. Additional free text key terms included: in vitro, tooth bleaching, placebo, negative control, overall CIELAB color change (ΔE*ab), change in shade guide units (ΔSGU), tooth color stabilization, evaluation time points, bovine teeth, and staining. Search was repeated in Web of Science but no additional articles were identified. A total of 11 studies were included for qualitative and quantitative analysis.

RESULTS

The meta-analysis of nine included studies that reported ΔE*ab values, revealed that the NC statistically exceeded the perceptibility threshold (PT) of 1.2 (P< 0.05). The estimate was 2.872 with lower and upper bounds of 1.955 and 3.790, respectively.

CLINICAL SIGNIFICANCE

Randomized controlled trials are gold standards to evaluate bleaching efficacy of different materials. However, in vitro studies offer a way to screen for potential bleaching efficacy. It is vital to determine an appropriate cut-off value for determining bleaching efficacy in vitro and further apply for clinical relevance.

Effect of Bleaching Gel Viscosity on Tooth Whitening Efficacy and Pulp Chamber Penetration: An In Vitro Study

Objectives:

Whitening efficacy has been related to hydrogen peroxide (HP) diffusion into tooth structure. However, little information is available relating rheological properties to whitening efficacy. The purpose was to evaluate the whitening efficacy and HP penetration level of a 10% HP gel at three different viscosities and to compare them to a strip delivery system.

Methods and Materials:

Extracted molars (n=120) were randomly assigned into five groups (n=24/ group): NC_MED (negative control; median): medium viscosity gel without HP; LOW: 10% HP gel (low viscosity experimental gel, Ultradent Products Inc); MED: 10% HP gel (medium viscosity experimental gel, Ultradent); HIGH: 10% HP gel (high viscosity gel, Ultradent); and CWS: Crest 3D Whitestrips 1-Hour Express (Procter & Gamble). All teeth were subjected to five 60-minute whitening sessions. Instrumental color measurements were performed at baseline (T0), and 1-day after each application (T1-T5), and 1-month after whitening (T6). HP penetration was estimated with leucocrystal violet and horseradish peroxidase. A Kruskal-Wallis test and post hoc Bonferroni test were performed to assess the difference in tooth color change and HP penetration among the groups (α=0.05).

Results:

Hydrogen peroxide penetration levels and overall color changes at T6 were 0.24 μg/mL / 2.80; 0.48 μg/mL / 8.48; 0.44 μg/mL / 7.72; 0.35 μg/mL / 8.49; 0.36 μg/mL / 7.30 for groups NC, LOW, MED, HIGH, and CWS, respectively. There was a significant difference for HP penetration, while there was no significant difference among the four experimental groups for tooth color change.

Conclusion:

Rheological properties should be considered when developing new whitening formulations.

Evidence-Based Practice Knowledge, Attitude, Access and Confidence: A comparison of dental hygiene and dental students

Purpose: The purpose of this study was to evaluate whether current educational strategies at a dental institution in the United States made a difference in dental hygiene (DNHY) and dental students' (D3) learning outcomes in the four domains of evidence-based practice (EBP), knowledge, attitude, accessing evidence, and confidence (KACE), following a 12-week research design course.Methods: All participants DNHY (n=19) and D3 (n=96) enrolled in the research design course at Loma Linda University completed a paper KACE survey distributed on the first day of class. Students completed the KACE survey once more at the end of the 12-week course. Pre- and post-survey results were compared both within and between the DNHY and D3 student groups to identify the learning outcomes in the four domains of EBP; knowledge, attitude, accessing evidence, and confidence in EBP. Descriptive statistics were conducted to profile all variables in the study; the level of significance was set at α=0.05.Results: All DNHY students (n=19) completed the pre and post KACE surveys; of the D3 (n=96) students enrolled in the course 82% (n=79) competed the post-survey. Comparison of the survey results showed that both DNHY and D3 students demonstrated statistically significant increases in their level of knowledge and attitude (p < 0.05) towards EBP. In the attitude domain, DNHY students indicated more positive attitudes towards EBP (p < 0.001) than their D3 student cohorts. Neither group demonstrated significant changes in confidence in applying EBP (p > 0.05).Conclusion: DNHY and D3 students increased their knowledge and developed more positive attitudes towards EBP following a 12-week research design course. Study results identify improvement areas for EBP knowledge acquisition including determining levels of evidence, analysis of study results, and evaluating the appropriateness of research study designs through the use of validated EBP survey instrument.

Performance of two different digital evaluation systems used for assessing pre-clinical dental students' prosthodontic technical skills

INTRODUCTION

Proper integration of newly emerging digital assessment tools is a central issue in dental education in an effort to provide more accurate and objective feedback to students. The study examined how the outcomes of students' tooth preparation were correlated when evaluated using traditional faculty assessment and two types of digital assessment approaches. Specifically, incorporation of the Romexis Compare 2.0 (Compare) and Sirona prepCheck 1.1 (prepCheck) systems was evaluated. Additionally, satisfaction of students based on the type of software was evaluated through a survey.

MATERIAL AND METHODS

Students in a second-year pre-clinical prosthodontics course were allocated to either Compare (n = 42) or prepCheck (n = 37) systems. All students received conventional instruction and used their assigned digital system as an additional evaluation tool to aid in assessing their work. Examinations assessed crown preparations of the maxillary right central incisor (#8) and the mandibular left first molar (#19). All submissions were graded by faculty, Compare and prepCheck.

RESULTS

Technical scores did not differ between student groups for any of the assessment approaches. Compare and prepCheck had modest, statistically significant correlations with faculty scores with a minimum correlation of 0.3944 (P = 0.0011) and strong, statistically significant correlations with each other with a minimum correlation of 0.8203 (P < 0.0001). A post-course student survey found that 55.26% of the students felt unfavourably about learning the digital evaluation protocols. A total of 62.31% felt favourably about the integration of these digital tools into the curriculum.

CONCLUSIONS

Comparison of Compare and prepCheck showed no evidence of significant difference in students' prosthodontics technical performance and perception.

The Effect of Delivery System and Light Activation on Tooth Whitening Efficacy and Hydrogen Peroxide Penetration

PURPOSE

To evaluate the whitening efficacy of a new two-layer technology in-office system compared to a conventional gel-type system and determine hydrogen peroxide penetration (HPP) into the pulp cavity.

MATERIALS AND METHODS

Extracted molars (n = 60) were assigned to group NC: glycerol gel; group QPRO: 20% HP varnish (Zoom Quick Pro, Philips Oral Healthcare); group ZOOM_NL: 25% HP gel (Zoom Chairside Whitening); and group ZOOM_WL: 25% HP gel (Zoom Chairside Whitening) with light-activation. HPP levels were estimated with leucocrystal-violet and horseradish-peroxidase. Instrumental color measurements were performed at baseline (T₀ ), 1-day post first whitening (T₁ ), 1-day post second whitening (T₂ ), 1-day post third whitening (T₃ ), and 1-month post whitening (T₄ ). One-way analysis of variance followed by post hoc Tukey's HSD test was performed to detect difference in ΔE* and HP penetration levels (α = 0.05).

RESULTS

ΔE* of NC was lower than other groups, whereas ΔE* of ZOOM_WL was greater than the other three groups, at T₃ and T₄ . Mean HPP level obtained from ZOOM_WL (1.568 ± 0.753 μg/mL) was significantly greater than those obtained from the other groups, whereas the mean HPP level observed in NC group (-0.131 ± 0.003 μg/mL) was significantly lower than the other groups.

CONCLUSIONS

Tooth whitening efficacy and HPP levels vary based on whitening systems used.

CLINICAL SIGNIFICANCE

The two-layer technology in-office varnish system may be an alternative whitening option to reduce chair time in the office. (J Esthet Restor Dent 28:313-320, 2016).

Effect of Light-Activated Tooth Whitening on Color Change Relative to Color of Artificially Stained Teeth

PURPOSE

There is still controversy as to the efficacy of light activation used in tooth whitening. The purpose of this study was to evaluate the effect of light activation on tooth color change relative to the artificial dye color.

MATERIALS AND METHODS

Extracted human third molars (160) were randomly distributed into eight groups of 20 specimens each based on artificial staining and use of light activation. All groups received three 45-minute sessions of in-office whitening at 3-day intervals. Color measurements were performed with an intraoral spectrophotometer at baseline prior to staining (T0), after artificial staining (T1), 1-day--(T2), and 1-week--(T3) post-whitening. Color differences were calculated relative to after artificial staining color parameters (L*1, a*1, b*1) with the use of a software analysis program enabling synchronization of two images.

RESULTS

Within the same staining groups, the light-activated samples exhibited a greater color change than their nonlight-activated counterparts. However, only in the case of the yellow-stained samples at 1-day post-whitening was there a significant difference between the nonlight-activated and light-activated groups (Tukey's post hoc multiple comparison test for pairwise comparisons, p < 0.05).

CONCLUSIONS

Light activation is a valid method for enhancing the efficacy of tooth whitening with respect to overall color change and works best with yellow stains.

CLINICAL SIGNIFICANCE

Light activation is a valid method for enhancing the efficacy of tooth whitening with respect to overall color change and works best with yellow stains.

Time Course of Potassium Nitrate Penetration into the Pulp Cavity and the Effect of Penetration Levels on Tooth Whitening Efficacy

OBJECTIVES

To establish time-course of potassium nitrate (PN) penetration into the pulp cavity, and determine whether PN pretreatment would affect whitening efficacy.

MATERIALS AND METHODS

Extracted teeth (n = 100) were randomized into five groups of 20 specimens each. Relief ACP (Philips Oral Healthcare, Los Angeles, CA, USA) was applied for 0, 5, 15, 30, and 60 minutes for groups 15, respectively. A nitrate/nitrite assay kit was used for colorimetric detection of nitrate. Whitening was performed using a Zoom White Speed system (Philips Oral Healthcare) for 60 minutes. Tooth color was measured with a spectrophotometer at baseline (T0 ), 1-day post PN application (T1 ), 1-day post-whitening (T2 ), and 1-month post-whitening (T3 ). Kruskal-Wallis test was used to assess group differences in PN penetration and tooth color change.

RESULTS

PN penetration differed among all groups except 2 and 3. There were no differences among groups for any baseline color parameters (p > 0.30). At T2 there was no change relative to baseline for individual components L*, a*, and b*. At T3 and T4 there was significant change relative to baseline for ΔL*, Δb*, and ΔE*, for all groups.

CONCLUSIONS

PN penetration is time dependent and pretreatment with PN does not affect whitening efficacy.

CLINICAL SIGNIFICANCE

Postassium nitrate penetration into the pulp cavity occurred as early as 5 minutes after application, and pretreatment with potassium nitrate containing desensitizers did not adversely affect tooth whitening efficacy. (J Esthet Restor Dent 28:S14-S22, 2016).

Impact of Digital Tooth Preparation Evaluation Technology on Preclinical Dental Students' Technical and Self-Evaluation Skills

The aim of this study was to evaluate the effect of digital tooth preparation imaging and evaluation technology on dental students' technical abilities, self-evaluation skills, and the assessment of their simulated clinical work. A total of 80 second-year students at one U.S. dental school were assigned to one of three groups: control (n=40), E4D Compare (n=20), and Sirona prepCheck (n=20). Students in the control group were taught by traditional teaching methodologies, and the technology-assisted groups received both traditional training and supplementary feedback from the corresponding digital system. Three outcomes were measured: faculty technical score, self-evaluation score, and E4D Compare scores at 0.30 mm tolerance. Correlations were determined between the groups' scores from visual assessment and self-evaluation and between the visual assessment and digital scores. The results showed that the visual assessment and self-evaluation scores did not differ among groups (p>0.05). Overall, correlations between visual and digital assessment scores were modest though statistically significant (5% level of significance). These results suggest that the use of digital tooth preparation evaluation technology did not impact the students' prosthodontic technical and self-evaluation skills. Visual scores given by faculty and digital assessment scores correlated moderately in only two instances.

Repeatability in Color Measurements of a Spectrophotometer using Different Positioning Devices

AIM

This study aimed to evaluate the repeatability of color measurements of an intraoral spectrophotometer with the use of three different methods by two operators.

MATERIALS AND METHODS

A total of 60 teeth were obtained, comprising 30 human maxillary teeth [central incisors (n = 10); canines (n = 10); molars (n = 10)] and 30 artificial teeth [lateral incisors (n = 10); premolar (n = 20)]. Multiple repeated color measurements were obtained from each tooth using three measuring methods by each of the two operators. Five typodonts with alternating artificial and human teeth were made. Measurements were taken by two operators with the Vita EasyShade spectrophotometer using the custom tray (CT), custom jig (CJ) and free hand (FH) method, twice, at an interval of 2 to 7 days. Friedman test was used to detect difference among the three color measuring methods. Post hoc Wilcoxon signed-rank test with Bonferroni correction applied was used for pair-wise comparison of color measurements among the three methods. Additionally, a paired-sample t-test was used to assess a significant difference between the two duplicated measurements made on the same tooth by the same operator for each color parameter and measuring method.

RESULTS

For operator A, mean (SD) overall color change-ΔE* (SD) perceived for FH, CT and CJ were 2.21(2.00), 2.39 (1.58) and 2.86 (1.92), respectively. There was statistically significant difference in perceived ΔE* in FH vs CJ (p = 0.0107). However, there were no significant differences between FH and CT (p = 0.2829) or between CT and CJ (p = 0.1159). For operator B mean ΔE* (SD) for FH, CT and CJ were 3.24 (3.46), 1.95 (1.19) and 2.45 (1.56), respectively. There was a significant difference between FH and CT (p = 0.0031). However, there were no statistically significant differences in ΔE* in FH vs CJ (p = 0.3696) or CT vs CJ (p = 0.0809).

CONCLUSION

The repeatability of color measurements was different among the three measuring methods by operators. Overall, the CT method worked well for both operators.

CLINICAL SIGNIFICANCE

The use of a custom tray with apertures can improve the repeatability of color measurements of an intraoral spectrophotometer.

Evaluation of Stain Penetration by Beverages in Demineralized Enamel Treated With Resin Infiltration

PURPOSE

To evaluate stain penetration by different beverages in artificially demineralized human teeth treated with resin infiltration.

METHODS AND MATERIALS

Sixty extracted human permanent molars were demineralized, treated with resin infiltration (Icon), and immersed in four different beverages (coffee, grape juice, iced tea, and distilled water; N=15) for four weeks. After aging, teeth in the distilled water group were stained with 2% methylene blue for 24 hours. All teeth were sectioned, and stain penetration was evaluated under light microscopy. Chi-square test, independent and paired sample t-test, analysis of variance with the Fisher least significant difference post hoc test, and the Kruskal-Wallis test were used to analyze the results (p<0.05).

RESULTS

Resin infiltration-treated surfaces (Icon surfaces) had statistically significant fewer samples with presence of stain penetration compared to untreated surfaces (control surfaces) (p<0.001). There was also a significant decrease in depth of stain penetration in Icon surfaces compared to the control surfaces (p<0.001). Among tested beverage groups, iced tea showed significantly greater depth of stain penetration (0.134±0.029 mm), followed by grape juice (0.118±0.047 mm), methylene blue (0.022±0.019 mm), and coffee (0.008±0.017 mm; p<0.001).

CONCLUSION

Both Icon and control surfaces exhibit stain penetration by different beverages (iced tea, grape juice, and coffee). However, resin-infiltrated enamel surfaces allow significantly less depth of stain penetration compared to untreated surfaces. The iced tea group presents greatest depth of stain penetration, followed by grape juice, methylene blue, and coffee.

Erosion Potential of Tooth Whitening Regimens as Evaluated with Polarized Light Microscopy

AIMS

Tooth whitening is a widely utilized esthetic treatment in dentistry. With increased access to over-the-counter (OTC) systems concerns have been raised as to potential adverse effects associated with overuse of whitening materials. Therefore, this study aimed to evaluate enamel erosion due to different whitening regimens when used in excess of recommended guidelines.

MATERIALS AND METHODS

Extracted human teeth (n = 66) were randomly divided into 11 groups (n = 6/group). Specimens were exposed to OTC products: Crest Whitestrips and 5-minute natural white and a do-it-yourself (DIY) strawberry whitening recipe. Within each regimen, groups were further divided per exposure time: specimens receiving the recommended product dosage; 5 times the recommended dosage; and 10 times the recommended dosage. Negative and positive controls were treated with grade 3 water and 1.0% citric acid, respectively. Specimens were nail-varnished to limit application to a 1 × 4 mm window. Following treatment, specimens were sectioned and erosion (drop in μm) measured using polarized light microscopy. Two-sample t-test was used to detect difference in amount of enamel erosion between negative and positive groups, while one-way analysis of variance (ANOVA), followed by post hoc Dunnett's test was used to detect difference between set of treatment groups and negative control groups or among all experimental groups.

RESULTS

There was significant difference in mean amount of enamel erosion (p < 0.0001). Mean enamel erosion for positive control group was significantly greater than that for negative control group (23.50 vs 2.65 μm). There was significant effect for type of treatments on enamel erosion [F(9,50) = 25.19; p < 0.0001]. There was no significant difference between the negative control and each of treatment groups (p > 0.05 for all instances), except for Natural White_10 times treatment group (p < 0.0001) that was significantly greater than the negative control group (14.82 vs 2.65 μm).

CONCLUSION

Caution is advised when using certain over-the-counter products beyond recommended guidelines as there is potential for enamel erosion.

CLINICAL SIGNIFICANCE

Enamel erosion due to the overuse of whitening products varies for different modalities and products. Therefore, caution is advised when using certain over-the-counter products beyond recommended guidelines, as there is potential for enamel erosion.

Effect of Computer-Assisted Learning on Students' Dental Anatomy Waxing Performance

The aim of this study was to evaluate the impact of computer-assisted learning on first-year dental students' waxing abilities and self-evaluation skills. Additionally, this study sought to determine how well digital evaluation software performed compared to faculty grading with respect to students' technical scores on a practical competency examination. First-year students at one U.S. dental school were assigned to one of three groups: control (n=40), E4D Compare (n=20), and Sirona prepCheck (n=19). Students in the control group were taught by traditional teaching methodologies, and the technology-assisted groups received both traditional training and supplementary feedback from the corresponding digital system. Five outcomes were measured: visual assessment score, self-evaluation score, and digital assessment scores at 0.25 mm, 0.30 mm, and 0.35 mm tolerance. The scores from visual assessment and self-evaluation were examined for differences among groups using the Kruskal-Wallis test. Correlation between the visual assessment and digital scores was measured using Pearson and Spearman rank correlation coefficients. At completion of the course, students were asked to complete a survey on the use of these digital technologies. All 79 students in the first-year class participated in the study, for a 100% response rate. The results showed that the visual assessment and self-evaluation scores did not differ among groups (p>0.05). Overall correlations between visual and digital assessment scores were modest though statistically significant (5% level of significance). Analysis of survey responses completed by students in the technology groups showed that profiles for the two groups were similar and not favorable towards digital technology. The study concluded that technology-assisted training did not affect these students' waxing performance or self-evaluation skills and that visual scores given by faculty and digital assessment scores correlated moderately.

Spectrophotometric Evaluation of Potassium Nitrate Penetration Into the Pulp Cavity

OBJECTIVES

The aim of this study was to evaluate the penetration level of potassium nitrate-containing desensitizers or whitening materials into the pulp cavity with regard to the concentration and viscosity of the formulation.

METHODS AND MATERIALS

Fifty extracted human molar teeth were prepared and randomized into five groups of 10 specimens each. The control received a 30-minute treatment without any treatment material; the other four groups corresponded to treatment with DayWhite, a 14% hydrogen peroxide whitening material containing potassium nitrate; PreviDent 5000 Sensitive, a desensitizing toothpaste; Relief ACP, a desensitizing gel; or UltraEZ, a desensitizing gel. Potassium nitrate penetration levels were measured spectrophotometrically based on the Griess assay method. Treatment materials were measured for viscosity as a function of shear rate through the use of a cone-and-plate rheometer.

RESULTS

Nitrate penetration levels were significantly different among the five groups (p<0.0001, Kruskal-Wallis test). After adjustment for multiple comparisons using an overall 0.05 level of type I error, the distribution of nitrate penetration values was found to differ significantly among all groups with the exception of DayWhite (median: 10.72 μM) and UltraEZ (median: 9.22 μM), which differed significantly from other groups but not from each other. The highest levels of nitrate penetration value were observed for PreviDent (median: 27.61 μM) followed by Relief ACP (median: 19.64 μM). The lowest penetration level was observed for the control group (median: 3.41 μM). Stable end-point viscosities of 11.43 ± 0.67 Pa/s, 1.33 ± 0.06 Pa/s, 0.85 ± 0.09 Pa/s, and 0.40 ± 0.01 Pa/s were observed for UltraEZ, ReliefACP, DayWhite, and PreviDent, respectively.

CONCLUSION

Potassium nitrate included in different formulations can penetrate the enamel and dentin within 30 minutes. The level of potassium nitrate penetration is influenced by concentration and may also be partly affected by the viscosity of the material as well as other constituents of proprietary preparations.

Evaluation of an Innovative Digital Assessment Tool in Dental Anatomy

AIM

The E4D Compare software is an innovative tool that provides immediate feedback to students' projects and competencies. It should provide consistent scores even when different scanners are used which may have inherent subtle differences in calibration. This study aimed to evaluate potential discrepancies in evaluation using the E4D Compare software based on four different NEVO scanners in dental anatomy projects. Additionally, correlation between digital and visual scores was evaluated.

MATERIALS AND METHODS

Thirty-five projects of maxillary left central incisors were evaluated. Among these, thirty wax-ups were performed by four operators and five consisted of standard dentoform teeth. Five scores were obtained for each project: one from an instructor that visually graded the project and from four different NEVO scanners. A faculty involved in teaching the dental anatomy course blindly scored the 35 projects. One operator scanned all projects to four NEVO scanners (D4D Technologies, Richardson, TX, USA). The images were aligned to the gold standard, and tolerance set at 0.3 mm to generate a score. The score reflected percentage match between the project and the gold standard. One-way ANOVA with repeated measures was used to determine whether there was a significant difference in scores among the four NEVO scanners. Paired-sample t-test was used to detect any difference between visual scores and the average scores of the four NEVO scanners. Pearson's correlation test was used to assess the relationship between visual and average scores of NEVO scanners.

RESULTS

There was no significant difference in mean scores among four different NEVO scanners [F(3, 102) = 2.27, p = 0.0852 one-way ANOVA with repeated measures]. Moreover, the data provided strong evidence that a significant difference existed between visual and digital scores (p = 0.0217; a paired - sample t-test). Mean visual scores were significantly lower than digital scores (72.4 vs 75.1). Pearson's correlation coefficient of 0.85 indicated a strong correlation between visual and digital scores (p < 0.0001).

CONCLUSION

The E4D Compare software provides consistent scores even when different scanners are used and correlates well with visual scores.

CLINICAL SIGNIFICANCE

The use of innovative digital assessment tools in dental education is promising with the E4D Compare software correlating well with visual scores and providing consistent scores even when different scanners are used.

Employment of Reservoirs in At-Home Whitening Trays: Efficacy and Efficiency in Tooth Whitening

AIM

This study aimed to determine the efficacy of trays made with and without reservoirs, in conjunction with time and cost evaluations, by measuring color change with home whitening procedures.

MATERIALS AND METHODS

Extracted human maxillary teeth (central incisors n = 20; canines n = 20; molars n = 20) and 60 artificial teeth (lateral n = 20; premolar n = 40) were mounted into ten typodonts. Tray fabrication was completed such that a block-out resin reservoir was placed on half of the buccal surface of the tray, while the other half remained without a reservoir. Whitening with custom fabricated trays was performed based on two different whitening regimens, where each regimen was assigned to five typodonts: Night-time: Opalescence PF 10% carbamide peroxide for 8 hours daily and Day-time: Philips DayWhite 9.5% hydrogen peroxide for 30 minutes, twice daily. Both systems were applied for 1 week. To evaluate tooth shade, the VITA Easyshade® Advance 4.0 spectrophotometer was used. Color measurements were obtained at baseline (T1), 1-day post-whitening (T2), and 1 month post-whitening (T3). One-way ANOVA, followed by post-hoc Tukey's HSD test, was used to detect significant difference in the overall color change (ΔE*) among the four groups at T2 and T3. Additionally, paired-sample t-test was used to assess difference in ΔE* between T2 and T3 treatment within each of four techniques of tray fabrication.

RESULTS

No significant difference in ΔE* was found among the four groups at T2 and T3 (p > 0.05 in each instance). There were significant differences in mean ΔE* between T2 and T3 treatment for the day white treatment groups without reservoir (6.96 vs 10.19 respectively; p = 0.0026) and with reservoirs (6.23 vs 9.79 respectively; p = 0.0031).

CONCLUSION

The use of reservoirs does not have a significant effect on whitening efficacy, regardless of type of whitening material and regimen.

CLINICAL SIGNIFICANCE

The use of custom fabricated trays with or without reservoirs were equally effective in whitening teeth.

Efficacy of Do-It-Yourself Whitening as Compared to Conventional Tooth Whitening Modalities: An In Vitro Study

Aim

To evaluate the efficacy of do-it-yourself (DIY) whitening as compared to conventional tooth whitening modalities using different shade assessment tools.

Methods and Materials

Extracted human molars (120) were randomly distributed to six groups (n=20). Whitening was performed according to manufacturer's directions for over-the-counter, dentist-dispensed for home use, and in-office whitening. DIY whitening consisted of a strawberry and baking soda mix. Additionally, negative and positive controls were used. Two evaluators used the Vita Classical (VC) and Vita Bleachedguide 3D-Master with interpolated numbers (BGi) for visual assessment at baseline and one-week, one-month, and three-month postwhitening. Instrumental measurements were performed with a spectrophotometer. Kruskal-Wallis procedure was used to assess color changes among groups and intraclass correlation (ICC) to evaluate agreement between evaluators.

Results

DIY exhibited lower color change (ΔSGUVC, ΔSGUBGi, ΔE*, where SGU = shade guide unit and E = overall color change) compared to other whitening groups at all time points (p&lt;0.05). ICC demonstrated very good agreement between evaluators with VC and BGi at each time point. Both shade guides were related with each other and strongly related to instrumental measurements (p&lt;0.05).

Conclusions

DIY whitening was the least effective whitening modality. Both VC and BGi are related with each other and have good correlation with instrumental measurements.

Dental anatomy grading: comparison between conventional visual and a novel digital assessment technique

Conventional grading of dental students' projects in preclinical courses has mainly relied on visual evaluation by experienced instructors. The purpose of this study was to compare conventional visual grading in a dental anatomy course at one U.S. dental school to a novel digital assessment technique. A total of sixty samples comprised of two sets of faculty wax-ups (n=30), student wax-ups (n=15), and dentoform teeth of tooth #14 (n=15) were used for this study. Two additional faculty members visually graded the samples according to a checklist and then repeated the grading after one week. The sample wax-up with the highest score based on the visual grading was selected as the master model for the digital grading, which was also performed twice with an interim period of one week. Descriptive statistics and signed rank tests for systematic bias were used for intra- and interrater comparisons. The intraclass correlation (ICC) was used as a measure of intra- and interrater reliability. None of the faculty members achieved the minimum acceptable intrarater agreement of 0.8. Interrater agreement was substantially less than intrarater agreement for the visual grading, whereas all measures of intrarater agreement were greater than 0.9 and considered excellent for the digital assessment technique. These results suggest that visual grading is limited by modest intrarater reliability and low interrater agreement. Digital grading is a promising evaluation method showing excellent intrarater reliability and correlation. Correlation for visual and digital grading was consistently modest, partly supporting the potential use of digital technology in dental anatomy grading.

Effect of various tooth whitening modalities on microhardness, surface roughness and surface morphology of the enamel

The purpose of this study was to evaluate the effect of four whitening modalities on surface enamel as assessed with microhardness tester, profilometer, and scanning electron microscopy (SEM). Whitening was performed according to manufacturer's directions for over-the-counter (OTC), dentist dispensed for home use (HW) and in-office (OW) whitening. Do-it-yourself (DIY) whitening consisted of a strawberry and baking soda mix. Additionally, negative and positive controls were used. A total of 120 enamel specimens were used for microhardness testing at baseline and post-whitening. Following microhardness testing specimens were prepared for SEM observations. A total of 120 enamel specimens were used for surface roughness testing at baseline and post-whitening (n = 20 per group). Rank-based Analysis of Covariance was performed to compare microhardness and surface roughness changes. Tests of hypotheses were two-sided with α = 0.05. There was a significant difference in Knoop hardness changes (ΔKHN) among the groups (Kruskal-Wallis test, p < 0.0001). Significant hardness reduction was observed in the positive control and DIY group (p < 0.0001). Mean surface roughness changes (ΔRa) were significantly different among the groups (Kruskal-Wallis test, p < 0.0001). Surface roughness increased in the OTC group (p = 0.03) and in the positive control (p < 0.0001). The four whitening modalities-DIY, OTC, HW and OW induced minimal surface morphology changes when observed with SEM. It can be concluded that none of the four whitening modalities adversely affected enamel surface morphology. However, caution should be advised when using a DIY regimen as it may affect enamel microhardness and an OTC product as it has the potential to increase surface roughness.

Influence of Application Techniques on Contact Formation and Voids in Anterior Resin Composite Restorations

This study evaluated the influence of three different application techniques on contact formation and voids in anterior resin composite restorations. Artificial ivorine teeth were randomly assigned to three experimental groups, with 20 specimens in each group. One operator performed all restorations using the Teflon tape, pull-through, or bioclear matrix technique. The treatment time required for each restoration was recorded. An examiner blinded to the treatment group performed the visual evaluation of six criteria, including proper contact formation. The restored teeth were cut to yield a total of 180 sections for microscopic evaluation. The Kruskal-Wallis procedure was performed to evaluate the significance of treatment time, number of voids, percent porosity area, and void diameter. There were significant differences in treatment time among the three groups (p&lt;0.05). The bioclear matrix technique required the least time for the treatment of one diastema closure (p&lt;0.05). The Teflon tape technique resulted in proper contact formation in 80% of specimens, a rate that was significantly lower than that associated with the pull-through and bioclear matrix techniques (p&lt;0.05). Out of 540 imaging areas 160 images were free of voids. The number of voids and the percent porosity area were not significantly different among the three techniques (p&gt;0.05). However, the mean void diameter was greater with the bioclear matrix technique compared to the other two techniques (p&lt;0.05).

Evaluation of bleaching efficacy and erosion potential of four different over-the-counter bleaching products

PURPOSE

To evaluate the bleaching efficacy and erosion potential of various over-the-counter bleaching products following a test method specified in ISO 28399.

METHODS

Specimens were prepared from bovine molars, stained in tea solution, embedded and randomly assigned to six groups of 10 enamel and dentin specimens each. Color was assessed at baseline, 1 day and 1 month post-bleaching with the Vita Bleachedguide 3D Master shade guide. Surface roughness changes (deltaRa), determined by baseline and post-treatment values were measured with a profilometer. The negative (NC) and positive control (PC) was treated with grade 3 water and 1.0% citric acid, respectively. Over-the-counter products were used according to manufacturer's instructions. Brite Teeth Pro (BT), Natural White 5-Minute Whitening (NW), Luster Premium White (LP), and Crest 3D Whitestrips (WS) represented a brush-on-paint system, tray system, light-activated system and adhesive-strip system, respectively. Kruskal-Wallis procedure was used to compare surface roughness changes among groups. Color change was assessed with Friedman-test and stratified by hard tissue type with alpha= 0.05.

RESULTS

WS was the only group demonstrating color changes in enamel and dentin (P< 0.05). There were no differences in deltaRa for enamel and dentin among NC, BT, LP, and WS. NW showed increase in deltaRa in dentin (P< 0.05), while PC demonstrated an increase in deltaRa regardless of hard tissue type (P< 0.05).

Direct measurement of stain retention in third molars

AIM

To directly determine the mass of dye retained in teeth following exposure to aqueous solutions of Rhodamine B and to correlate tooth color modifications.

MATERIALS AND METHODS

Extracted third molars (25) were selected and sectioned at the cementoenamel junction for coronal staining. Pulp tissue was removed and teeth sonicated to remove debris. Teeth were kept in deionized water for 12 hours and subsequently weighed. They were then stained for 4 hours in 5 ml of Rhodamine B dye at two different concentrations. The samples were then subjected to two 8 hours rinses in deionized water. The tooth shade was recorded with a commercially available intraoral spectrophotometer (Vita Easyshade Compact, Vita Zahnfabrik, Bad Säckingen, Germany) at baseline (T1), after dye immersion (T2), and after water rinsing (T3). A standard absorption curve was then used to calculate the dye mass in the rinse solutions as well as the post- treatment stain solutions. All solution optical absorption curves were recorded using a laboratory research spectrophotometer (Cary 300, Agilent, USA). The mass of dye in each solution was then calculated from the standard curve relating optical absorption to aqueous dye concentration.

RESULTS

An average change in the CIE (a) values of 8.0 ± 0.3 were observed for concentrations of Rhodamine B similar to the optical appearance of wine or other darkly colored juices while an increase of 10× in concentration gave values too high to measure using a standard intraoral spectrophotometer. By measuring the optical absorbance of the staining solutions before and after the staining process, we were able to measure dye retention of 54 ± 26 micrograms per gram of tooth.

CONCLUSION

While no significant correlation could be found between the amount of stain retention in the dentition and the tooth shade due to the high uncertainties in the spectroscopic measurements, we were able to show that this method should admit such comparisons for future research.

CLINICAL SIGNIFICANCE

The development of a reliable chromophore infiltration model may provide standardized and reproducible results in evaluating tooth whitening efficacy.