The use of DryShield versus rubber dam isolation systems among pediatric patients with different airway patency: A randomized clinical trial.

Objectives: This randomized clinical trial aimed to evaluate the impact of DryShield isolation (DSI) and rubber dam isolation (RDI) system usage on vital signs, behavior, pain and discomfort, and chairside time required among children with different airway patencies based on the Modified Mallampati Classification (MMC). Material and methods: Healthy, cooperative children who required fissure sealant in at least two contralateral, fully erupted, permanent first molars were included. Airway patency was determined by two trained and calibrated dentists using the MMC. The participants were categorized based on their MMC scores into patent airways (classes I and II) and non-patent airways (classes III and IV). The dental procedure was videotaped during treatment, and vital signs, including arterial oxygen saturation, heart rate, and blood pressure, were recorded every 3 min. The participants' subjective pain and discomfort were evaluated using a previously validated Arabic interview questionnaire and a validated Arabic version of the Wong-Baker Faces Pain Rating Scale. The participants' behavior and behavioral pain were evaluated utilizing the Frankl Behavior Scale and the face, legs, activity, cry, and consolability scales, respectively. Results: There were no significant differences in any of the vital signs between DSI and RDI. DSI use yielded a significant reduction in chairside time (P < 0.001) and was more bothersome (P < 0.001) than RDI use among all participants, regardless of airway patency. DSI was associated with significantly better behavior during the dental procedure (P = 0.002) and less behavioral pain (P < 0.001) among all participants, regardless of airway patency. Conclusion: Irrespective of airway patency, DSI outperformed RDI in terms of behavior, pain, and procedure duration; however, DSI was characterized by noise, pressure on soft tissues, and an increased tendency to induce gag reflexes.

Timing, reasons, and predictors for first dental visits among children seen at two university hospitals.

BACKGROUND: Dental caries is the most common chronic childhood disease. The recommended age for the first dental visit (FDV) is 1 year, yet a minority of children visit before the age of 3 years. AIM: The aim of the study was to estimate the patterns of and predictors for dental visits among a sample of children. DESIGN: Parents of children between the ages of 6 months and 18 years, who attended the paediatric dentistry clinics and the well-baby clinics, were recruited. A validated questionnaire was used to collect data. Logistic regression was utilized to assess the predictors of ever visiting a dentist. RESULTS: The mean age at FDV was 5.8 ± 2.1 years. Parents' belief of not needing to see a dentist was the most common barrier to visiting a dentist (33%). Among the reasons for FDV, caries and pain were the most common (45% and 20%, respectively). Predictors of ever visiting a dentist were children who are not an only child and children of parents who visited a dentist themselves. CONCLUSION: Children visited the dentist at an age older than that recommended, and the reasons for FDV were mainly caries and its consequences.

Visual Analysis of Panoramic Radiographs among Pediatric Dental Residents Using Eye-Tracking Technology: A Cross-Sectional Study.

The aim of this cross-sectional study was to explore the eye tracking (ET) performance of postgraduate pediatric dental students in correctly detecting abnormalities in different sets of panoramic radiographs. This observational study recruited postgraduate pediatric dental students to evaluate seven panoramic radiographs. RED-m® SMI software (Sensomotoric Instruments, Teltow, Germany) was used to track the participants' eye movements as they looked at the radiographs. The data collected for areas of interest (AOIs) included revisit counts, fixation counts, fixation times, entry times, and dwell times. Univariate and bivariate analyses were conducted to summarize the participants' characteristics and ET measures. The overall percentage of correctly located AOIs was 71.7%. The residents had significantly more revisits and fixation counts in AOIs located in one sextant than in multiple sextants (p < 0.001). Similar patterns were observed for fixation and dwell times (p < 0.001), but not for entry time. Heatmaps showed that the highest density of fixations was on the AOIs and the residents fixated more on dentition than on bony structures. In single-sextant radiographs, residents had significantly more revisits and fixation counts for AOIs compared to those of multiple sextants. Residents had slower entry times and dwelled less on AOIs located in multiple sextant(s). The reported findings can direct dental educators to develop a standardized scan scheme of panoramic radiographs to minimize misdiagnosis.

The Use of Eye-Tracking Technology in Pediatric Orofacial Clefts: A Systematic Review and Meta-Analysis.

This systematic review and meta-analysis assessed the quality of the peer-reviewed literature and evaluated the usefulness of eye-tracking technology in evaluating observers' perceptions of pediatric patients with orofacial clefts. PubMed, Science Direct, Wiley, and Web of Science were searched. Articles were screened in accordance with the Preferred Reporting Items for Systematic Review and Meta-analysis guidelines, and their methodological quality was assessed. Of the 10,254 identified studies, 12 were included. Eleven studies were cross-sectional, and one was a prospective cohort study. The main areas of interest analyzed were the eyes, nose, and mouth. Nine studies used assessment scales to analyze the link between perceived attractiveness and visualization patterns and measures. For the fixation duration outcome, six studies were eligible for inclusion in the meta-analysis. All studies reported on fixation duration in milliseconds and reported on a standard deviation. The meta-analysis demonstrated a significant difference in the measurements between the control groups and the patients with orofacial clefts. This might indicate the usefulness of eye-tracking technology as a metric for assessing the success of cleft repairs based on the perceptions of different populations. Future studies should be comprehensively reported on for comparability and reproducibility purposes.

Recurrent caries models to assess dental restorations: A scoping review.

OBJECTIVES: To review the literature on recurrent caries models used to evaluate restorative materials, compare reported methodology and parameters, and devise specific recommendations to be considered in future investigations. DATA: The following were extracted: study design, sample characteristics, source of teeth, name of restorations compared including controls, recurrent caries model type, type of demineralizing and remineralizing solutions, type of biofilm used, methods to detect recurrent caries. SOURCES: Literature searches were performed in OVID Medline, EMBASE, SCOPUS, and Cochrane Library. STUDY SELECTION: For a study to be included, it had to examine dental materials for tooth restoration purposes only with a valid control group and evaluate restorative dental materials regardless of the form of the teeth caries model used or nature of the tooth structure used. A total of 91 studies were included. Most of the studies presented were in vitro. Human teeth were the main source of specimens utilized. Around 88% of the studies used specimens without an artificial gap, and 44% used a chemical model. S. mutans was the main bacterial species used in microbial caries models. CONCLUSION: The findings of this review provided an insight into the performance of available dental materials assessed using different recurrent caries models, yet this review cannot be used as a guideline for material selection. Selecting the appropriate restorative material relies on several patient-related factors such as microbiota, occlusion, and diet that are not comprehensively taken into consideration in recurrent caries models and thus hinder reliable comparison. CLINICAL SIGNIFICANCE: Due to the heterogenicity of variables among studies on the performance of dental restorative materials, this scoping review aimed to provide insights for dental researchers concerning the available recurrent caries models, testing methods used, and aspects of comparison between these materials including their characteristics and limitations.

The effect of virtual reality distraction on anxiety level during dental treatment among anxious pediatric patients: a randomized clinical trial.

This study evaluated the effect of Virtual Reality Distraction (VRD) on dental anxiety among anxious children undergoing prophylactic dental treatment by utilizing both subjective (Venham Anxiety and Behavioral Rating Scale (VABRS)) and objective (heart rate (HR) and salivary cortisol level (SCL)) measures. This randomized controlled study included 36 (6- to 14-year-old) healthy and anxious children who needed prophylactic dental treatment and had a history of previous dental treatment. The eligible children's anxiety level was evaluated using a modified version of the Abeer Dental Anxiety Scale-Arabic version (M-ACDAS) and those who scored at least 14 or more out of 21 were included. Participants were randomly distributed to either the VRD or control group. In the VRD group, participants wore the VRD eyeglasses during prophylactic dental treatment. In the control group, subjects received their treatment while watching a video cartoon on a regular screen. The participants were videotaped during the treatment, and their HR was recorded at four time points. Also, a sample from each participant's saliva was collected twice, at the baseline and after the procedure. The mean M-ACDAS score at baseline in the VRD and the control groups was not statistically significant (p = 0.424). At the end of the treatment, the SCL was significantly lower in the VRD group (p < 0.001). Neither the VABRS (p = 0.171) nor the HR significantly differed between the VRD and control groups. Virtual reality distraction is a non-invasive method that has the potential to significantly reduce anxiety during prophylactic dental treatment among anxious children.

Clinical Effects of Dental Caries on the Quality of Life of Paediatric Patients Aged 8-10 Years: Utilisation of the PUFA Index.

PURPOSE: Saudi children have poor oral health; however, little data are available on the effects of dental caries and its clinical complications on the oral health-related quality of life (OHRQoL) in school-aged children. This study evaluated the impact of caries and its clinical effects on the OHRQoL of a sample of 8- to 10-year-old children attending King Abdulaziz University Hospital. MATERIALS AND METHODS: The following variables were assessed for each child: sociodemographic data, OHRQoL using an Arabic-validated Child Perception Questionnaire for 8- to 10-year-old children (CPQ8-10), and two global health rating questions. Caries and its clinical effects on oral health were also assessed using the decayed-missing-filled teeth (dmft/DMFT) and pulpal involvement, ulceration, fistula, and abscess (pufa/PUFA) indices. Descriptive statistics of the sociodemographic variables and responses to the CPQ8-10 questions are presented as absolute values and percentages. The CPQ8-10 scores between children with different dmft/DMFT and pufa/PUFA scores were compared. RESULTS: In total, 169 children participated in this study. The means ± SD of dmft and DMFT were 5.03 ± 2.5 and 2.35 ± 1.7, respectively. However, the pufa and PUFA scores were 1.03 ± 1.6 and 0.05 ± 0.2, respectively. The most common oral health complaint affecting OHRQoL was food stuck to the teeth. Participants with higher dmft and pufa/PUFA scores had statistically significantly higher CPQ8-10 scores than did their counterparts. CONCLUSION: High dmft and pufa/PUFA scores have a statistically signifcantly negative effect on the OHRQoL among healthy 8- to 10-year-old children. Worse global health ratings correlate with lower OHRQoL.

Access to dental care for children with special health care needs: a cross-sectional community survey within Jeddah, Saudi Arabia.

The aim of this study was to investigate the level of dental care access among children with special health care needs (CSHCN) in Jeddah, Saudi Arabia and the barriers hindering this access. Data of this cross-sectional study were obtained from self-administered surveys distributed through seven CSHCN centers. Children with autistic spectrum disorder (ASD), Down syndrome, cerebral palsy, and developmental delay were included. Univariate and bivariate analyses were conducted to describe the data. A total of 602 study participants were included in the analyses. Only 24.9% of the participated caregivers routinely visited the dentist for their CSHCN. Half of CSHCN caregivers found difficulties obtaining dental treatment. This trend was significantly greater in 12-18 years old children (p = 0.013) and in families commuting for more than one hour to dental clinics (p = 0.045). The most common reported barrier was fear of the dentist (61.6%) followed by child uncooperativeness (37.8%) and treatment costs (27.8%). CSHCN lack sufficient dental care for a variety of reasons, primarily fear of dentists, child uncooperativeness, and treatment costs. Dentists require more training and education to facilitate better access to dental care for CSHCN.

Faculty perception on clinical shadowing: A concurrent mixed methods study.

PURPOSE: This mixed methods study aims to investigate faculty members' perceptions of early clinical exposure through clinical shadowing program (CSP) at one academic dental institution. METHODS: After ethical approval was received, concurrent data collection using quantitative and qualitative methods was integrated for this study design. For the quantitative data, a validated instrument (Likert scale) was distributed to all basic and clinical science faculty members regarding the CSP. Qualitative semi-structured interviews of basic and clinical science faculty members were conducted to explore their perceptions of the CSP. Descriptive statistics were completed for the quantitative data, and thematic analysis was carried out for the transcribed interviews. RESULTS: Faculty members from basic and clinical sciences participated in this mixed methods study, 97% (n = 74) participants in the quantitative and 12 participants in the qualitative. The majority of faculty (67%; n = 44) strongly agreed that CSP helps predoctoral students in the application of basic science knowledge to clinical practice. All basic science respondents (n = 10; 100%) and many clinical science faculty (60%; n = 35) strongly agreed that CSP requires coordination between basic and clinical science educators (p = 0.042). Some faculty suggested the inclusion of training for educators on the program and regular periodic student assessments of the program's effectiveness. CONCLUSION: The current study reported positive faculty perception toward the proposed method of integration. Furthermore, opportunities to foster coordination between basic and clinical science educators may be provided by administrators to strengthen the existing CSP framework.

Effects of thermal cycling on mechanical and antibacterial durability of bioactive low-shrinkage-stress nanocomposite.

OBJECTIVES: Recent studies developed low-shrinkage-stress composite with remineralizing and antibacterial properties to combat secondary caries and increase restoration longevity. However, their long-term durability in thermal cycling is unclear. The objectives of this study were to develop an antibacterial, remineralizing and low-shrinkage-stress composite, and to investigate its durability in thermal cycling for 20,000 cycles, equivalent to two years of clinical life. METHODS: The resin consisted of urethane dimethacrylate (UDMA) and triethylene glycol divinylbenzyl ether (TEG-DVBE). Composites were made with 5% dimethylaminohexadecyl methacrylate (DMAHDM) and 20% of nanoparticles of amorphous calcium phosphate (NACP). Composites were thermal cycled at 5°C and 55°C for 20,000 cycles. A human salivary biofilm model was used to evaluate antibiofilm activity before and after thermal cycling. RESULTS: After 20,000 cycles, the flexural strength of bioactive low-shrinkage-stress composite matched commercial control with no antibacterial activity (p > 0.05). Surface roughness was clinically acceptable at less than 0.2 µm. UV+NACP+DMAHDM composite reduced the total microorganisms, total streptococci, and mutans streptococci by 2-5 logs, compared to commercial composite. Biofilm lactic acid production was reduced by 11 folds. The antibacterial performance was maintained after thermal cycling, with no decrease after 20,000 cycles. CONCLUSIONS: Bioactive low-shrinkage-stress composite possessed good mechanical properties that matched commercial composite both before and after thermal cycling. The new composite had potent antibacterial activity, which was maintained and did not decrease after thermal cycling. CLINICAL SIGNIFICANCE: The new bioactive low-shrinkage-stress composite could reduce polymerization shrinkage stress and release calcium and phosphate ions, with good mechanical properties and strong antibacterial function that were durable after thermal cycling. These properties indicate great potential for inhibiting recurrent caries and increasing the restoration longevity.

Novel low-shrinkage-stress bioactive nanocomposite with anti-biofilm and remineralization capabilities to inhibit caries.

Background/purpose: A common reason for dental composite restoration failure is recurrent caries at the margins. Our objectives were to: (1) develop a novel low-shrinkage-stress, antibacterial and remineralizing resin composite; (2) evaluate the effects of dimethylaminohexadecyl methacrylate (DMAHDM) on mechanical properties, biofilm inhibition, calcium (Ca) and phosphate (P) ion release, degree of conversion, and shrinkage stress on the new low-shrinkage-stress resin composite for the first time. Material and methods: The resin consisted of urethane dimethacrylate (UDMA) and triethylene glycol divinylbenzyl ether (TEG-DVBE) with high resistance to salivary hydrolytic degradation. Composites were made with 0%-8% of DMAHDM for antibacterial activity, and 20% of nanoparticles of amorphous calcium phosphate (NACP) for remineralization. Mechanical properties and Streptococcus mutans biofilm growth on composites were assessed. Ca and P ion releases, degree of conversion and shrinkage stress were evaluated. Results: Adding 2-5% DMAHDM and 20% NACP into the low-shrinkage-stress composite did not compromise the mechanical properties (p > 0.05). The incorporation of DMAHDM greatly reduced S. mutans biofilm colony-forming units by 2-5 log and lactic acid production by 7 folds, compared to a commercial composite (p < 0.05). Adding 5% DMAHDM did not compromise the Ca and P ion release. The low-shrinkage-stress composite maintained a high degree of conversion of approximately 70%, while reducing the shrinkage stress by 37%, compared to a commercial control (p < 0.05). Conclusion: The bioactive low-shrinkage-stress composite reduced the polymerization shrinkage stress, without compromising other properties. Increasing the DMAHDM content increased the antibacterial effect in a dose-dependent manner.

A comparison of manikin and live patient-based dental hygienist clinical licensing exam.

OBJECTIVES: The Central Regional Dental Testing Service in the United States administered its first manikin-based (M) dental hygiene licensing exam in 2020. The aim of this study was to compare the licensure exam results of dental hygiene students examined using manikins versus live patients. METHODS: After obtaining the ethical approval, the de-identified exam scores of three different cohorts (2019, 2020, and 2021) were collected from the academic record database of Carrington College, Dental Hygiene School, San Jose, California. The exam scores of the students were grouped based on the exam format conducted: either M or patient-based (P). Mann-Whitney U test and two-tailed Fisher's exact were used to compare the scores of the groups. RESULTS: The scores of 108 dental hygiene graduates between 2019 and 2021 were analyzed. The study included 65 participants examined in group P and 43 participants in group M. There was no significant difference in the mean score between groups P and M (p = 0.46) or in the passing rate between the two groups (p = 0.52). However, a higher first-attempt passing rate was noted in the M group. Moreover, calculus removal scores were comparable between the two examination groups (p = 0.18). CONCLUSION: The findings of this study supported the comparability of both manikin and live P exam outcomes. Therefore, the use of M exams may be considered for future examinations. Further studies are needed in other settings to confirm the efficacy of M exams in evaluating the students' clinical performance.

A novel homozygous SLC13A5 whole-gene deletion generated by Alu/Alu-mediated rearrangement in an Iraqi family with epileptic encephalopathy.

Biallelic loss-of-function (LoF) of SLC13A5 (solute carrier family 13, member 5) induced deficiency in sodium/citrate transporter (NaCT) causes autosomal recessive developmental epileptic encephalopathy 25 with hypoplastic amelogenesis imperfecta (DEE25; MIM #615905). Many pathogenic SLC13A5 single nucleotide variants (SNVs) and small indels have been described; however, no cases with copy number variants (CNVs) have been sufficiently investigated. We describe a consanguineous Iraqi family harboring an 88.5 kb homozygous deletion including SLC13A5 in Chr17p13.1. The three affected male siblings exhibit neonatal-onset epilepsy with fever-sensitivity, recurrent status epilepticus, global developmental delay/intellectual disability (GDD/ID), and other variable neurological findings as shared phenotypical features of DEE25. Two of the three affected subjects exhibit hypoplastic amelogenesis imperfecta (AI), while the proband shows no evidence of dental abnormalities or AI at 2 years of age with apparently unaffected primary dentition. Characterization of the genomic architecture at this locus revealed evidence for genomic instability generated by an Alu/Alu-mediated rearrangement; confirmed by break-point junction Sanger sequencing. This multiplex family from a distinct population elucidates the phenotypic consequence of complete LoF of SLC13A5 and illustrates the importance of read-depth-based CNV detection in comprehensive exome sequencing analysis to solve cases that otherwise remain molecularly unsolved.

Low-shrinkage-stress nanocomposite: An insight into shrinkage stress, antibacterial, and ion release properties.

The aims are: (a) To develop the first low-shrinkage-stress nanocomposite with antibacterial and remineralization capabilities through the incorporation of dimethylaminododecyl methacrylate (DMAHDM) and nanoparticles of amorphous calcium phosphate (NACP); (b) to investigate the effects of the new composite on biofilm inhibition, mechanical properties, shrinkage stress, and calcium (Ca) and phosphate (P) ion releases. The low-shrinkage-stress resin consisted of urethane dimethacrylate and triethylene glycol divinylbenzyl ether. Composite was formulated with 3% DMAHDM and 20% NACP. Mechanical properties, shrinkage stress, and degree of conversion were evaluated. Streptococcus mutans biofilm growth on composites was assessed. Ca and P ion releases were measured. The shrinkage stress of the low-shrinkage-stress composite containing 3% DMAHDM and 20% NACP was 36% lower than that of traditional composite control (p < 0.05), with similar degrees of conversion of 73.9%. The new composite decreased the biofilm colony-forming unit by 4 log orders and substantially reduced biofilm lactic acid production compared to control composite (p < 0.05). Incorporating DMAHDM to the low-shrinkage-stress composite did not adversely affect the Ca and P ion release. A novel bioactive nanocomposite was developed with low shrinkage stress, strong antibiofilm activity, and high levels of ion release for remineralization, without undermining the mechanical properties and degree of conversion.

Long-term antibacterial activity and cytocompatibility of novel low-shrinkage-stress, remineralizing composites.

A low-shrinkage-stress (LSS), antibacterial and remineralizing nanocomposite was recently developed; however, validation of its long-term antibacterial potency in modulating human salivary-derived biofilm is an unmet need. This study aimed to evaluate the antibacterial effect of the bioactive LSS composite before and after aging in acidic solution for 90 days using a multi-species biofilm model, and to evaluate its cytotoxicity. The LSS composite consisted of urethane dimethacrylate (UDMA) and triethylene glycol divinylbenzyl ether (TEG-DVBE), 3% dimethylaminohexadecyl methacrylate (DMAHDM) and 20% nanoparticles of amorphous calcium phosphate (NACP). Biofilm colony-forming units (CFU), lactic acid production, and confocal laser scanning microscopy (3D biofilm) were evaluated before and after three months of aging. Cytotoxicity was assessed against human gingival fibroblasts (HGF). The new LSS composite presented the lowest biofilm CFU, lactic acid and biofilm biomass, compared to controls (n = 6, p < 0.05). Importantly, the new composite exhibited no significant difference in antibacterial performance before and after 90-day-aging, demonstrating long-term antibacterial activity (p > 0.1). The LSS antibacterial and remineralizing composite presented a low cell viability at original extract that has increased with further dilutions. In conclusion, this study spotlighted that the new bioactive composite not only had a low shrinkage stress, but also down-regulated the growth of oral biofilms, reduced acid production, maintained antibacterial activity after the 90-day-aging, and did not compromise the cytocompatibility.

Bioactive low-shrinkage-stress nanocomposite suppresses S. mutans biofilm and preserves tooth dentin hardness.

Recurrent dental caries is one of the main reasons for resin composite restoration failures. This study aimed to: (1) develop a bioactive, low-shrinkage-stress, antibacterial and remineralizing composite and evaluate the sustainability of its antibacterial effect against Streptococcus mutans (S. mutans) biofilms; and (2) evaluate the remineralization and cariostatic potential of the composite containing nanoparticles of amorphous calcium phosphate (NACP) and dimethylaminohexadecyl methacrylate (DMAHDM), using dentin hardness measurement and a biofilm-induced recurrent caries model. The antibacterial and remineralizing low-shrinkage-stress composite consisted of urethane dimethacrylate (UDMA) and triethylene glycol divinylbenzyl ether (TEG-DVBE), 3% DMAHDM and 20% NACP. S. mutans biofilm was used to evaluate antibiofilm activity, before and after 3 months of composite aging in acidic solution. Human dentin was used to develop a recurrent caries biofilm-model. Adding DMAHDM and NACP into low shrinkage-stress composite did not compromise the flexural strength. The low-shrinkage-stress composite with DMAHDM achieved substantial reductions in biofilm colony-forming units (CFU), lactic acid production, and biofilm biomass (p < 0.05). The low-shrinkage-stress DMAHDM+NACP composite exhibited no significant difference in antibacterial performance before and after 3 months of aging, demonstrating long-term antibacterial activity. Under S. mutans biofilm acidic attack, dentin hardness (GPa) was 0.24 ± 0.04 for commercial control, and 0.23 ± 0.03 for experimental control, but significantly higher at 0.34 ± 0.03 for DMAHDM+NACP group (p < 0.05). At an instrumental compliance of 0.33 µm/N, the polymerization shrinkage stress of the new composite was 36% lower than that of a traditional composite (p < 0.05). The triple strategy of antibacterial, remineralization and lower shrinkage-stress has great potential to inhibit recurrent caries and increase restoration longevity. Statement of Significance Polymerization shrinkage stress, masticatory load over time as well as biochemical degradation can lead to marginal failure and secondary caries. The present study developed a new low-shrinkage-stress, antibacterial and remineralizing dental nanocomposite. Polymerization shrinkage stress was greatly reduced, biofilm acid production was inhibited, and tooth dentin mineral and hardness were preserved. The antibacterial composite possessed a long-lasting antibiofilm effect against cariogenic bacteria S. mutans. The new bioactive nanocomposite has the potential to suppress recurrent caries at the restoration margins, protects tooth structures, and increases restoration longevity.

Novel low-shrinkage-stress nanocomposite with remineralization and antibacterial abilities to protect marginal enamel under biofilm.

OBJECTIVES: Polymerization shrinkage stress may lead to marginal damage, microleakage and failure of composite restorations. The objectives of this study were to : (1) develop a novel nanocomposite with low-shrinkage-stress, antibacterial and remineralization properties to reduce marginal enamel demineralization under biofilms; (2) evaluate the mechanical properties of the composite and calcium (Ca) and phosphate (P) ion release; and (3) investigate the cytotoxicity of the new low-shrinkage-stress monomer in vitro. METHODS: The low-shrinkage-stress resin consisted of urethane dimethacrylate (UDMA) and triethylene glycol divinylbenzyl ether (TEG-DVBE), and 3 % dimethylaminohexadecyl methacrylate (DMAHDM) and 20 % calcium phosphate nanoparticles (NACP) were added. Mechanical properties, polymerization shrinkage stress, and degree of conversion were evaluated. The growth of Streptococcus mutans (S. mutans) on enamel slabs with different composites was assessed. Ca and P ion releases and monomer cytotoxicity were measured. RESULTS: Composite with DMAHDM and NACP had flexural strength of 84.9 ±â€¯10.3 MPa (n = 6), matching that of a commercial control composite. Adding 3 % DMAHDM did not negatively affect the composite ion release. Under S. mutans biofilm, the marginal enamel hardness was 1.2 ±â€¯0.1 GPa for the remineralizing and antibacterial group, more than 2-fold the 0.5 ±â€¯0.07 GPa for control (p < 0.05). The polymerization shrinkage stress of the new composite was 40 % lower than that of traditional composite control (p < 0.05). The new monomers had fibroblast viability similar to that of traditional monomer control (p > 0.1). CONCLUSION: A novel low-shrinkage-stress nanocomposite was developed with remineralizing and antibacterial properties. This new composite is promising to inhibit recurrent caries at the restoration margins by reducing polymerization stress and protecting enamel hardness.

Novel antibacterial calcium phosphate nanocomposite with long-term ion recharge and re-release to inhibit caries.

Short-term studies on calcium-phosphate (CaP) ion-rechargeable composites were reported. The long-term rechargeability is important but unknown. The objectives of this study were to investigate nanocomposite with strong antibacterial and ion-recharge capabilities containing dimethylaminododecyl methacrylate (DMAHDM) and nanoparticles of amorphous calcium phosphate (NACP), and evaluate long-term ion-recharge by testing for 12 cycles (taking 6 months to complete) for the first time. Three groups were tested: (1) Heliomolar control; (2) Resin+20%NACP+50%glass; (3) Resin+3%DMAHDM+20%NACP+50%glass. Biofilm acid and colony-forming units (CFU) were measured. Ion-recharge was tested for 12 cycles. NACP-DMAHDM composite reduced biofilm acid, and reduced CFU by 4 logs. High levels of ion releases were maintained throughout 12 cycles of recharge, maintaining steady-state releases without reduction in 6 months (p>0.1), representing long-term remineralization potential. Bioactive nanocomposite demonstrated long-term ion-rechargeability for the first time, showed remineralization and potent anti-biofilm functions, with promise for tooth restorations to combat caries.