Adhesive sonic agitation improves bonding durability to class-II cavity preparation.

The purpose of this study was to evaluate the effect of adhesive sonic agitation on resin-dentin micro-tensile bond strength (µTBS) and interfacial morphology at the gingival wall of class-II cavity preparation. Seventy-two molars with prepared class-II cavities were divided into six groups (n = 12) according to the bonding mode; etch-and-rinse (E&R) or self-etch (SE) and application protocol of the universal adhesive (UA) employed (Clearfil Universal Bond Quick, Kuraray Noritake); following the manufacturer instructions (MI), manual agitation for 20 s (20s), or sonic agitation for 20 s using a modified sonic micro-brush mounted on EndoActivator device, Dentsply Sirona, (sonic). Restored teeth were sectioned into resin-dentin beams and slaps and µTBS was evaluated at 1 week (1w) and after thermocycling (10k). µTBS data were analyzed using the linear mixed-effects modeling with specific contrast (p < 0.05). The resin-dentin interfacial morphology was evaluated using a scanning electron microscope. Adhesive sonic agitation resulted in significantly higher µTBS means in both E&R and SE modes, compared to MI group. The µTBS of MI group showed significant reduction upon aging when applied in SE mode. Sonic agitation was associated with enhanced adhesive infiltration into dentin specially in E&R mode. Sonic agitation of UA using modified sonic micro-brush attached to EndoActivator device significantly improved the resin-dentin µTBS and interfacial morphology at the gingival wall of class-II cavity preparation.

Dental students' academic performance before and after the Covid-19 pandemic: A retrospective analysis.

Delivering quality education to students with fair assessment strategies is a key indicator of an excellent educational institution. The present study explored the impact of the COVID-19 pandemic on the academic performance of dental students in terms of the evaluations/grades awarded to them before and during the pandemic. The targeted groups were dental students, studying in the third year of 2018-2019 and 2020-2021 academic years. The sample size included all male and female students who enrolled and completed the following courses: pre-clinical fixed prosthodontics (SDS333), pre-clinical removal prosthodontics (SDS323), clinical operative dentistry-1 (RDS313), and pre-clinical endodontics (RDS323). Evaluations for students who did not complete the requirements were not included in the statistical analysis. Paired sample statistics were used for comparisons between the different groups at p < 0.05. Results revealed statistically significant differences (p ≤ 0.05) for all the course pairs. It was found that students' grades for all the courses during the pandemic year were higher compared to the grades before the pandemic. While female students demonstrated the highest mean difference (6.13) before and during the pandemic year for RDS323, males demonstrated the highest mean difference (8.14) for SDS323. However, both male and female students demonstrated the lowest mean difference (0.25 and 2.03, respectively) for SDS333. The grades were higher during the COVID-19 pandemic. Overall, female students achieved higher grades than male students.

Microtensile Bond Strength of Bioactive Pit and Fissure Sealants Bonded to Primary and Permanent Teeth.

BACKGROUND: Sealing occlusal pits and fissures is an effective preventive measure against dental caries. Pit and fissure sealants (PFS) should be strongly bonded to the teeth to prevent partial or complete loss of the sealant, which may limit its preventive effect. OBJECTIVE: The objective of the study was to compare the microtensile bond strength (µTBS) of bioactive resin-based sealants (Bio-RBS) and resin-based sealants (RBS), with and without the use of a bonding agent, to the enamel of primary and permanent teeth. METHODS: One hundred and twenty caries-free primary molar specimens and 120 permanent molar specimens were divided to eight groups (30 specimens per group), both primary and permanent teeth were sealed with a Bio-RBS BioCoatTM (Premier®, Plymouth Meeting, PA, USA) or with a RBS ClinproTM (3M ESPE, Saint Paul, MN, USA), with or without the use of a bonding agent (Prime & Bond NT; Dentsply, Inc., Charlotte, NC, USA). Half the specimens were aged with 5000 thermal cycles, and all specimens were tested for the µTBS and failure mode. RESULTS: The mean µTBS of aged Bio-RBS was higher in permanent teeth than primary teeth, and the aging process reduced the µTBS of RBS more than that of Bio-RBS. Moreover, the addition of a bonding agent improved the µTBS of aged RBS in permanent teeth. CONCLUSION: We concluded that Bio-RBS exhibit superior µTBS than RBS when applied to permanent teeth.

Using bonding agent prior to pits and fissure sealant application enhances the microtensile bond strength and the interface morphology.

BACKGROUND: A pits and fissures sealant is an effective method for preventing dental caries. Using a bonding agent before applying the sealant may increase its retention. This study aimed to compare the microtensile strength (µTBS) of a fissure sealant with and without a bonding agent and to characterize the enamel-sealant interface using confocal laser scanning microscopy (CLSM). The null hypothesis was that the use of a bonding agent before fissure sealant application would not change the microtensile strength or the enamel-sealant interface. MATERIALS AND METHODS: Twenty caries-free premolars were used. Each tooth was divided into four parts. The first two parts were assigned to the bonded group, where a bonding system was used before sealant application. The remaining two parts were treated only with a fissure sealant (i.e., the nonbonded group). In each group, the µTBS was examined after 24 h (n = 20) and after a 3-month aging period (n = 20). Five other caries-free extracted premolars were used to assess the enamel-sealant interface using CLSM. Two-way analysis of variance (ANOVA) and Pearson chi-square statistical analysis tests were used to analyze the µTBS and the enamel-sealant interface, respectively. RESULTS: The mean µTBS for the bonded group was significantly higher (p = 0.001) in the immediate group (36.87 ± 14.95 MPa) and the aged group (31.08 ± 15.88 MPa) than in the respective nonbonded groups (19.77 ± 9.67 MPa and 19.52 ± 14.14 MPa). The µTBS was not significantly different in either group after aging (p = 0.46 [bonded group] and p = 0.98 [nonbonded group]). In addition, using a dental adhesive, before applying a fissure sealant resulted in a significantly higher (53%) resin penetration into the enamel with the continuous integrity of the resin. CONCLUSION: The use of a bonding agent before the application of fissure sealant resulted in superior microtensile bond strength immediately and after aging. In addition, the enamel-sealant interface characteristics were improved.

Influence of Photodynamic therapy and different gingival retraction agents on bond integrity of composite to dentin.

AIM: The present study was undertaken to evaluate the influence of gingival retraction agents (Expasyl and Viscostat) and different conditioning methods (Total-etch, Self-etch, and PDT) on bond integrity of composite to dentin. MATERIAL AND METHODS: One hundred and eighty, third molars were collected cleaned and disinfected in thymol solution. The specimens were rooted vertically up to cementoenamel junction within polyvinyl cylinders (PVC). Based on gingival retraction materials samples were divided into three groups (n = 60). Group A: dentin applied with Expasyl; Group B: Viscostat was applied on dentin and Group C: Control. Dentin surface was treated with different surface conditioners. Etch and rinse, PDT MBP, and Two-step self-etch. A bonding agent was applied and composite buildup was done. Samples were placed in the universal testing machine for SBS. Bond failure was assessed using a stereomicroscope. Analysis of variance (ANOVA) and Tukey's post hoc test compared the means and standard deviations (SD) after SBS testing (p = 0.05). RESULTS: The highest score of bond strength was exhibited by group C1 (21.14 ±â€¯1.05 MPa-Etch & rinse + Tetric-N- Bond) whereas group C2 (12.15 ±â€¯0.28 -PDT MBPS + Tetric-N-Bond, No treatment group) demonstrated the lowest SBS. Based on the application of haemostatic agent, bond values among subgroups A1 (18.75 ±â€¯1.05 MPa - Expasyl + Etch & rinse + Tetric-N-bond) and B1 (17.84 ±â€¯0.11 MPa -Viscostat + Etch & rinse + Tetric-N-Bond) was comparable (p>0.05). Based on the conditioning methods, bond scores among groups C1 (21.14 ±â€¯1.05 MPa -Etch & rinse + Tetric-N- Bond) and C3 (19.05 ±â€¯1.28 MPa -Clearfill SE) were comparable (p >0.05). CONCLUSION: Viscostat and Expasyl result in compromised bond integrity of composite restoration to dentin in etch and rinse and self-etch group compared to no treatment group. However, the pre-application of Viscostat and Expasyl on dentin conditioned with PDT improved bond integrity of composite resin.

Effect of Aging on the Microhardness of Different Resin-based Fluoride-releasing Fissure Sealants: An In Vitro Study.

AIM: The aim of the present study was to evaluate the effect of aging on the microhardness score [Vickers hardness number (VHN)] of different resin-based fluoride-releasing sealants compared to non-fluoride resin-based sealants. MATERIALS AND METHODS: A total of 48 extracted sound molars that were sectioned mesiodistally were used. In the current study, four types of sealants were compared: Group A, a resin-based non-fluoride-releasing pit and fissure sealant (Eco-S sealant) served as a control. Groups B, C, and D received resin-based fluoride-releasing pit and fissure sealants Helioseal F, Fissurit F, and Embrace™ WetBond, respectively. Subsequently, each group was further divided into immediate and aged subgroups. The samples had been evaluated regarding their microhardness using a pyramidal diamond indenter of a Vickers hardness test at two-time intervals: Immediately and after the aging process through thermocycling. RESULTS: There were no statistically significant differences between mean VHN and material types (p = 0.72). Aging appeared to significantly increase the mean VHN (p = 0.001). The interaction model between material type and time factor showed that the effect of aging differs by the material type, where the VHN of the Embrace™ group increased significantly after aging from 24.33 ± 5.60 to 31.70 ± 3.59 (p = 0.001). CONCLUSION: While there were no significant differences in the microhardness of commonly used fluoride-releasing fissure sealants, time appears to significantly increase the mean microhardness score (VHN), especially in the Embrace™ group. CLINICAL SIGNIFICANCE: Embrace™ WetBond fissure sealant showed a significant improvement in the mean microhardness score (VHN) with time. However, clinical studies with long-term follow-up are needed to confirm our results.

Effect of universal adhesives on microtensile bond strength to hybrid ceramic.

BACKGROUND: The aim of this study was to evaluate the effect of universal adhesives (UA) and silane on the microtensile bond strength (µTBS) of resin cement to a hybrid ceramic Vita Enamic (VE). METHODS: VE specimens were acid etched using hydrofluoric acid (HF) and were assigned to three groups (n = 10) based on the applied bonding technique. In group 1 (S), a silane-based primer was used as a surface treatment prior to the application of a resin cement (Variolink Esthetic DC). In group 2, a silane-containing UA, Clearfil Universal Bond (CUB) was used for the surface treatment, and in group 3, A silane-free UA, Tetric N-Bond Universal (TNU) was used for surface treatment. Resin cement build-ups were prepared. The bonded specimens were sectioned into resin-ceramic beams. Half of the beams of each group were stored for 24 h at 37 °C and the other half were subjected to a thermo-cycling aging. The microtensile bond strength (µTBS) was measured at a crosshead speed of 0.5 mm/min. Failure modes were assessed accordingly. Data were analyzed using a) two-way analysis of variance ANOVA followed by one-way ANOVA and Tukey tests between groups and b) independent t-test to detect differences (α = 0.05) for each group. The surface topographies of the ceramic surface were evaluated using scanning electron microscopy. RESULTS: The results showed that silane-based primer (S) application resulted in significantly higher (p < 0.05) µTBS values after 24 h and after thermocycling compared to both silane-containing UA (CUB) and silane-free UA (TNU). The µTBS values of all groups were significantly reduced after thermocycling. No statistically significant difference was observed between the µTBS of CUB and TNU after 24 h. However, TNU showed significantly higher µTBS after thermocycling. Different failure modes were observed, and adhesive failure was the most common in all groups. Marked surface topographic changes were observed following HF etching. CONCLUSION: It is concluded that, the UAs tested cannot be recommended as substitutes to the silanization of Hybrid ceramic.

Comparison of the antibacterial activity of calcium silicate- and epoxy resin-based endodontic sealers against Enterococcus faecalis biofilms: a confocal laser-scanning microscopy analysis.

This study assessed the antibacterial activity of BioRoot RCS in comparison with that of the Totalfill BC and AH Plus sealers against Enterococcus faecalis biofilms in dentinal tubules using confocal laser-scanning microscopy. Sixty-six root dentin halves were prepared and sterilized. Three sections were used to ensure sterilization. The remaining were inoculated with E. faecalis. Three specimens were examined to verify the viability of biofilms. The sixty specimens were randomly divided into four groups: AH Plus, BioRoot RCS, Totalfill BC sealer, and no sealer. The specimens were incubated for 1, 7, and 30 days. The specimens were stained and four corners of each disc were scanned. Statistical analysis was performed using two-way ANOVA and Tukey's post hoc test. Almost half of the bacteria were dead in BioRoot RCS group on day 1 and in Totalfill BC group on day 7. All sealers killed significantly more bacteria than the control after 30 days (P < .05). On day 7, Totalfill BC showed a significantly higher percentage of dead bacteria than BioRoot RCS (P < .05). On day 30, the BioRoot RCS group registered the highest percentage of dead cells (61.75%), which was significantly higher than the percentages of the AH Plus and Totalfill BC groups (P < .05). Calcium silicate-based root canal sealers exerted antimicrobial effects against E. faecalis biofilms. The antibacterial activity of BioRoot RCS was significantly higher than that of the Totalfill BC and AH Plus sealers after 30 days of exposure.

The Effect of Chlorhexidine and Listerine® Mouthwashes on the Tensile Strength of Selected Absorbable Sutures: An In Vitro Study.

BACKGROUND: Suturing plays a critical role in the healing of surgical wounds. The tensile strength of suture materials indicates the ability of the material to withstand stress during knotting and protect the wound during an extended period of healing. OBJECTIVE: An in vitro study was conducted to determine the effect of two commercially available mouthwashes on the tensile strength and breakage mode of two absorbable intraoral sutures. MATERIALS AND METHODS: Two common absorbable sutures, Vicryl® and Monocryl®, both with 4-0 and 5-0 gauges were used. A total of 400 specimens were sutured around rubber rods and immersed in three thermostatically controlled experimental conditions: artificial saliva, 0.2% chlorhexidine gluconate (Parodontax® extra), and essential oils-based rinse (Listerine® Zero™), and these were compared to a nonimmersed dry condition. All specimens were stored in an incubator at 37°C. Tensile strengths were assessed after days 1, 3, 7, 10, and 14 of immersion using a universal Instron® testing machine. The maximum load for suture breakage and the location of the point of breakage were assessed. RESULTS: Unlike Monocryl® 4-0, the tensile strength of both gauges of Vicryl® sutures significantly increased in chlorhexidine and Listerine®. There was a significant decrease in the strength for all suture types after day 10, regardless of the immersion solution. Listerine® significantly reduced the tensile strength of Monocryl® 5-0. CONCLUSION: Oral surgeons and periodontists should be cautious when prescribing commercial mouthwashes for patients relative to their selection of suture materials. However, further studies are needed to understand the molecular changes in sutures when exposed to chemical solutions found in mouthwashes.

Association Between Dental Caries and Body Mass Index in Schoolchildren Aged Between 14 and 16 Years in Riyadh, Saudi Arabia.

BACKGROUND: Dental caries and obesity are multifactorial diseases that have common risk factors. Studies worldwide reported varied outcomes about the association between dental caries and obesity. There is no published study that investigates this association among schoolchildren in Arabic countries. The aim of this study was to evaluate the relationship between dental caries (DMFT) and body mass index (BMI) for children aged between 14 and 16 years old in Riyadh, Saudi Arabia. The role of oral hygiene habits, parent's education, sugar consumption and physical activity in causing both diseases was also evaluated. METHODS: This is a cross-sectional study that involved 610 schoolchildren aged between 14 and 16 years. The children were selected from 12 boy's intermediate schools distributed in Riyadh city. A questionnaire that asked about demographic data, oral hygiene habits, parents' education, sugar consumption and physical activity was distributed. Then, the mean DMFT and BMI were calculated by collecting the information from dental examination, body weight and height. Multivariate logistic regression model was used to explain the relationship between the teeth health and the BMI. Moreover, multivariate linear regression was conducted to model the relationship between DMFT and BMI and the socioeconomic score, sugar consumption and physical activity. RESULTS: The prevalence of dental caries (DMFT > 0) was 54.1%. Around 32% of the schoolchildren were either overweight or obese. A statistically significant association between dental caries (DMFT) and BMI was found (P = 0.008). It was found that obese schoolchildren are 1.79 times higher to be with healthy teeth (P = 0.02). In addition, it was found that schoolchildren with higher socioeconomic status are 1.26 times higher to be with healthy teeth group (P = 0.005). Similarly, schoolchildren who reported that they are using the fluoridated toothpaste were 1.63 times higher to be within the healthy teeth group (DMFT = 0) when everything else is controlled. Physical activity level affects the schoolchildren BMI significantly (P < 0.001). CONCLUSIONS: The study showed a statistically significant association between dental caries and BMI for this study sample. Obese schoolchildren showed healthier teeth than others did. Fluoride toothpaste usage and socioeconomic score were associated significantly with dental caries.

An MMP-inhibitor modified adhesive primer enhances bond durability to carious dentin.

OBJECTIVES: To evaluate the effect of adding a matrix metalloproteinase (MMP) inhibitor (BB94, Batimastat) to the primer of a three-step etch and rinse adhesive system on caries-affected dentin (CaD) MMP activity, and to assess the effect of such an inclusion on the chemical content of the CaD-adhesive interface. METHODS: Caries-infected dentin (CiD) was excavated selectively from freshly extracted human carious teeth using a chemo-mechanical agent. Each tooth was sectioned into three slabs through the CaD retained cavity. These were treated with either Optibond FL "OB" (Kerr, Orange, USA) without MMP inhibitor, or with 500 µM BB94 prior to the application of OB primer and bond, or with OB primer that contained 5 µM BB94. In situ zymography and Raman micro-spectroscopy were used to investigate MMP activity and the changes in the chemical content at the CaD/adhesive interface, respectively. RESULTS: Data showed the use of OB adhesive with BB94 resulted in immediate interfacial MMP inhibition, by direct application (93.3%) and by means of a drug delivery system (80%), as demonstrated by in situ zymography. Raman imaging revealed 33% higher resin infiltration into MMP-inhibited adhesive interfaces (SE 3.88). SIGNIFICANCE: Through competitive inhibition by batimastat (BB94), a proportion of the MMPs found in CaD were inhibited immediately and irreversibly. Such a competitive mechanism brings the adhesive primer close to the collagen matrix and enhances the dental adhesive wettability, which is a proposed mechanism to explain the presence of more resin within the hybrid layer.