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.

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.

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.

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 (ε400 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) ε400 nm versus localized surface plasmon peak maxima; (3) ε400 nm versus hydrodynamic size. NTA for quantitative characterization of anisotropic nanoparticles could lead to future applications, including heterogeneous colloidal catalysis.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.