A systematic review and meta-analysis of randomized clinical trials comparing rotary canal instrumentation techniques with manual instrumentation techniques in primary teeth.

BACKGROUND: Use of rotary instruments in the root canals of permanent teeth is well known; however, there are no evidence-based recommendations on the effectiveness of rotary canal instrumentation techniques over manual instrumentation techniques during root canal treatment in primary teeth. AIM: To appraise the current literature on the effectiveness of rotary canal preparation techniques compared to manual techniques during root canal treatment in primary teeth. DATA SOURCES: MEDLINE, Embase, Cochrane Library, Scopus, PubMed and Web of Science (1 January 1991 to 3 January 2019). STUDY ELIGIBILITY CRITERIA, PARTICIPANTS AND INTERVENTIONS: Population: Children with primary teeth; Intervention: Rotary canal instrumentation; Control: Manual canal instrumentation; Outcomes: Success rates (clinical and/or radiographic), quality of root filling, instrumentation and root filling time, postoperative pain, cleaning effectiveness. STUDY APPRAISAL AND SYNTHESIS METHODS: Cochrane risk of bias tool 2.0 was used to ascertain the validity across five domains. Risk ratio (RR) for dichotomous variables and weighted mean difference for continuous variables were used as summary measures. The GRADE approach was used to assess the certainty of evidence using GRADE-pro software. RESULTS: A total of 13 trials were selected of 2471 records after screening of the databases. The RR of clinical success in rotary versus manual canal preparation technique was 1.01 (95% CI: 0.91-1.12; P = 0.913) at 6 months. The RR of radiographic success in rotary versus manual techniques was 0.97 (95% CI: 0.74-1.27; P = 0.805) at 6 months. The quality of root filling was not significantly different between the two groups (P = 0.062). The weighted mean difference of instrumentation time and canal filling time was significantly less with rotary techniques (P < 0.001); however, postoperative pain was non-significant across both techniques at 12, 24 and 72 h but significantly less with rotary techniques at 6 h (P < 0.001) and 48 h (P = 0.023). LIMITATIONS: Inclusion of only English literature. CONCLUSIONS AND IMPLICATIONS OF KEY FINDINGS: Rotary canal instrumentation had a similar clinical and radiographic success rate, less postoperative pain (at 6 and 48 h), and took less instrumentation time compared to manual instrumentation techniques (moderate level of evidence).

Effect of a novel quaternary ammonium silane cavity disinfectant on cariogenic biofilm formation.

OBJECTIVE: Evaluate effect of quaternary ammonium silane (QAS) cavity disinfectant on cariogenic biofilm. MATERIALS AND METHODS: Single- (Streptococcus mutans or Lactobacillus acidophilus), dual- (Streptococcus mutans/Lactobacillus Acidophilus), and multi-species (Streptococcus mutans, Actinomyces naeslundii, and Streptococcus sanguis) biofilms were grown on acid-etched dentine discs. Biofilms were incubated (120 min/37 °C) and allowed to grow for 3 days anaerobically. Discs (no treatment) served as control (group 1). Groups II, III, IV, and V were then treated with 2% chlorhexidine, and 2%, 5%, and 10% QAS (20 s). Discs were returned to well plates with 300 µL of bacterial suspension and placed in anaerobic incubator at 37 °C and biofilms redeveloped for 4 days. Confocal microscopy, Raman, CFU, and MTT assay were performed. RESULTS: Raman peaks show shifts at 1450 cm-1, 1453 cm-1, 1457 cm-1, 1460 cm-1, and 1462 cm-1 for control, 2% CHX, 2%, 5%, and 10% QAS groups in multi-species biofilms. There was reduction of 484 cm-1 band in 10% QAS group. CLSM revealed densely clustered green colonies in control group and red confluent QAS-treated biofilms with significantly lower log CFU for single/dual species. Metabolic activities of Streptococcus mutans and Lactobacillus acidophilus decreased with increasing QAS exposure time. CONCLUSION: Quaternary ammonium silanes possess antimicrobial activities and inhibit growth of cariogenic biofilms. CLINICAL SIGNIFICANCE: Available data demonstrated use of QAS as potential antibacterial cavity disinfectant in adhesive dentistry. Experimental QAS can effectively eliminate caries-forming bacteria, when used inside a prepared cavity, and can definitely overcome problems associated with present available cavity disinfectants.

Barriers to providing oral health care to pre-school children-differences between paediatric dentists' and general dental practitioners' beliefs.

BACKGROUND: The unmet dental needs of pre-school children indicate there are barriers in 'accessing' appropriate oral health care and this warrants consideration of care providers' beliefs. OBJECTIVE: To explore the beliefs and attitudes of dentists in Hong Kong towards providing oral health care to pre-school children; and to determine difference in attitudes between general dental practitioners (GDPs) and paediatric dentists (PDs). METHODS: A random sample of 476 GDPs (-25% of all registered dentists) and all registered PDs (28) were invited to participate in the study. Both groups were asked to complete the Barriers to Childhood Caries Treatment (BaCCT) questionnaire: a 29-item measure considering child, parent, dentist and health care system factors. Differences in attitudes of GDPs and PDs were examined in bivariate and regression analyses. RESULTS: The overall response rate of the study was 61.5% (310/504). There were significant differences in overall BaCCT scores and across all domains between GDPs and PDs (p < 0.05). Furthermore, variations across many aspects (as described at an item level) were apparent. Regression analyses confirmed differences in BaCCT between GDPs and PDs, controlling for practice and other factors. CONCLUSIONS: Differences exist between GDPs' and PDs' perceptions of barriers to care for early childhood caries. This has implications for how to address 'access' issues with likely implications on how to overcome barriers to care for pre-school children.

Development and evaluation of a Dental Patient Feedback on Consultation skills (DPFC) measure to enhance communication.

OBJECTIVES: To adapt an existing medical questionnaire on patient-provider communication for use in the dental setting, and to evaluate the performance of the measure in a first dental encounter (validity and reliability). METHODS: A patient feedback questionnaire on consultation skills was adapted for use in dental settings through content and convergent validity. A survey of dentist consultation skills was conducted among adults attending a teaching hospital. Patients self-completed a 16-item Dental Patient Feedback on Consultation skills (DPFC) questionnaire during their first dental consultations. Repeat assessments were conducted on -10% of the sample. Variations in DPFC responses (scale and item level) were examined in relation to socio-demographics and dental attendance pattern in bivariate and regression analyses. Internal reliability (Cronbach's alpha) and test-retest reliability (Intraclass Correlation Coefficient - ICC) were examined. RESULTS: A DPFC questionnaire was derived following minor modifications. The clarity of items ranged from 81.1-100% and content validity index ranged from 0.73-1.00. Exploratory item factor analysis showed a one-dimensional construct. The response rate to the survey was 90.5% (389/430). Variations in DPFC scores with respect to global rating of satisfaction were apparent (P < 0.001). Cronbach's alpha value was 0.94 and ICC value was 0.89. Bivariate and regression analyses identified dental attendance pattern as a key factor associated with DPFC (P < 0.05); but no significant differences were observed with respect to socio-demographic factors. CONCLUSIONS: A DPFC questionnaire was adapted with acceptable validity and reliability. Dental service utilization pattern was associated with dentist-patient clinical communication rather than socio-demographics.

Journal-based learning, a new learning experience building on PBL at HKU.

OBJECTIVE: To evaluate the effectiveness of a new journal-based learning (JBL) programme designed to equip students with skills necessary to understand dental research publications, thereby preparing them for continuing professional development. MATERIALS AND METHODS: A baseline evaluation of knowledge relating to key research terms was conducted on 52 final-year BDS students. 11 weekly seminars were conducted from 8 clinical disciplines driven by a reading list of 2-5 journal articles along with a series of 'guidance' questions relating to research terms and content knowledge aspects of each paper to focus their reading and learning. Seminars were facilitated by discipline experts with supporting notes. An exit test based on research process and terminologies for the programme was conducted with 4 repeated questions from the baseline assessment. A systematic marking scheme was used and the results analysed. A focus group was run to collect feedback regarding students' views and experiences on the JBL experience. FINDINGS: Students showed significant improvements over the baseline score. The mean score rose from 3.5 to 11.5 in the repeated questions (P < 0.001). The focus group revealed that students had learnt new information about journal classification, evidence level determination, new research terms and the structure of research papers. From the first 4 years of PBL, students recognized the importance of learning from research papers since year 1. However, JBL gave them a deeper understanding of research and the development of critical appraisal skills. IMPLICATIONS: JBL provided final-year students the opportunity to learn significantly more about dental research, terminologies, paper structure, critical analysis and content knowledge through active-learning small group seminars.

Effect of sleep on development of early childhood caries: a systematic review.

PURPOSE: To investigate the impact of sleep on the development of early childhood caries (ECC). METHODS: Seven electronic databases and grey literature were searched with various keyword combinations. Two reviewers independently selected studies, extracted data, and assessed the risk of bias using the Newcastle-Ottawa Scale. The studies were included if they evaluated the impact of sleep parameters on the caries experience or severity of ECC in children under 6 years of age. RESULTS: Four cross-sectional studies and two longitudinal studies were included. Children who had irregular bedtimes had a 66-71% higher chance of developing ECC. Children who slept after 11 pm might have a 74-85% higher chance of developing ECC. Children who slept less than 8 h during the night had a 30% increased risk of caries than children who slept more than 11 h. CONCLUSION: Irregular or late bedtime and fewer sleeping hours could be an independent risk factor for ECC. The risk of ECC might be related inversely in a dose-response manner to the number of sleep hours.

Self-perceived preparedness for dental practice amongst graduates of The University of Hong Kong's integrated PBL dental curriculum.

OBJECTIVES: To determine how prepared for dental practice graduates from the integrated problem-based learning (PBL) dental undergraduate curriculum at The University of Hong Kong (HKU) perceive themselves to be and to identify factors associated with self-perceived preparedness. MATERIALS AND METHODS: A postal questionnaire was sent to five cohorts of dentists who had graduated from HKU's integrated PBL curriculum between 2004 and 2008. Using a 4-point Likert scale, the questionnaire assessed the self-perceived level of preparedness in 59 competencies grouped in nine domains. Responses were dichotomised into 'poorly prepared' and 'well prepared'. RESULTS: The response rate was 66% (159/241). The mean proportion (±standard deviation) of respondents indicating well-preparedness was 72.0±15.1% overall, and for each domain was as follows: general patient management, 93.1±12.1%; practice management, 81.0±22.2%; periodontology and dental public health, 73.5±19.3%; conservative dentistry, 92.5±13.1%; oral rehabilitation, 62.8±24.0%; orthodontics, 23.0±32.9%; managing children and special-needs patients, 64.8±28.9%; oral and maxillofacial surgery, 52.2±25.2%; and drug and emergency management, 84.7±22.6%. The odds of self-perceived well-preparedness were increased for cohorts graduating in 2004 and 2005 and graduates working in a non-solo dental practice. CONCLUSIONS: Dental graduates of HKU's integrated PBL curriculum felt well prepared for the most fundamental aspects of dental practice. However, apparent deficiencies of training in orthodontics and oral and maxillofacial surgery will need to be addressed by continuing education, postgraduate training and planning for the new 6-year undergraduate curriculum in 2012.

Evaluation of developmentally hypomineralised enamel after surface pretreatment with Papacarie Duo gel and different etching modes: an in vitro SEM and AFM study.

PURPOSE: This study aimed at investigating the surface morphology and nanotopography of normal enamel (NE) and developmentally hypomineralised enamel (HE) when subjected to various pretreatment protocols under scanning electron microscopy (SEM) and atomic force microscopy (AFM). METHODS: Sixteen NE, 16 creamy/white (CW) HE and 16 yellow/brown (YB) HE specimens sectioned from extracted hypomineralised first permanent molars (FPMs) were included in this study. They were randomly distributed into 12 experimental groups (n = 4). Each group involved the following: (1) deproteinisation with Papacarie Duo® gel or no deproteinisation, and (2) the use of Scotchbond™ Universal Adhesive (Scotchbond) in self-etch (SE) mode or 37% phosphoric acid etchant. Subsequently, the surface morphology and nanotopography of pretreated enamel specimens were evaluated under SEM and AFM, respectively. RESULTS: SEM observation showed that deproteinisation with Papacarie Duo® gel before phosphoric acid etching led to favourable etching patterns. This was consistent across all groups irrespective of the type of enamel specimen and the severity of hypomineralisation. In contrast, AFM results identified three factors that influenced surface parameters: (1) type of enamel specimen, (2) severity of hypomineralisation and (3) etching mode. YB HE recorded higher surface roughness values than CW HE and NE when subjected to the same pretreatment protocol. Deproteinisation and the application of Scotchbond in SE mode led to minimal topographic changes; however, acid etching was associated with an increase in surface roughness. CONCLUSION: Deproteinisation with Papacarie Duo® gel followed by acid etching contributed to improved etching patterns on HE.

Health- and oral health-related quality of life among preschool children with autism spectrum disorders.

PURPOSE: To assess the health-related quality of life (HrQoL) and oral health-related quality of life (OHrQoL) of preschool children with autism spectrum disorders (ASD) and to determine the associated factors. METHODS: A case-control study of preschool children with and without ASD was undertaken. H&OHrQoL were assessed employing Pediatric Quality-of-Life Inventory Version 4.0 (PedsQL™ 4.0) and Early Childhood Oral Health Impact Scale (ECOHIS). Differences in PedsQL and ECOHIS scores were determined between groups and correlation between PedsQL and ECOHIS was explored. Regression analyses were conducted to determine key factors associated with H&OHrQoL. RESULTS: Parents of 510 children (253 cases and 257 controls) completed the H&OHrQoL questionnaire assessments. Significant difference in PedsQL (p < 0.001) and ECOHIS (p < 0.001) scores was apparent between children with and without ASD. There was a positive and weak correlation between PedsQL and ECOHIS scores (r = - 0.45, p < 0.01). In regression analyses, the presence of ASD was associated with an increased likelihood of having lower PedsQL (OR 0.10, 95% CI 0.06-0.15, p < 0.001) and higher ECOHIS scores (OR 2.34, 95% CI 1.60-3.42, p < 0.001). CONCLUSIONS: Differences in H&OHrQoL exist among preschool children with and without ASD. There was a significant but weak correlation between children's H&OHrQoL. Both H&OHrQoL were associated with autism spectrum disorders.

Effect of temperature on water sorption and solubility of dental adhesive resins.

OBJECTIVE: This study examined the effect of temperature on water sorption and solubility characteristics of four commercial dental adhesives. The null hypothesis tested was that temperature has no effect on the water sorption and solubility characteristics of these adhesives. METHODS: The tested materials were: three-step etch-and-rinse (All-Bond 2, AB), two-step etch-and-rinse (One-Step, OS), two-step self-etch (Clearfil SE Bond, SE) and one-step self-etch (Clearfil S3 Bond, S3) adhesives. Seven resin disks (6mm in diameterx1mm in thickness) were prepared from each tested material and were stored in deionized water at 23 degrees C, 37 degrees C and 55 degrees C. Water sorption and solubility of the resin disks were measured before and after water immersion and desiccation following two consecutive sorption and desorption cycles. The water sorption and solubility values obtained were analyzed using two-way ANOVA and Tukey's multiple comparison tests. The relationships between maximum water sorption, solubility and kinetics of water diffusion with temperature were evaluated by means of Pearson correlation statistic. RESULTS: OS exhibited the highest water sorption and solubility values in the second sorption-desorption cycle at 55 degrees C (p<0.001). This is followed by S3, SE and AB with no significant difference between SE and AB. Significant positive correlations were observed between maximum water sorption (r=0.307, p<0.01), solubility (r=0.244, p<0.05), water sorption (r=0.651, p<0.001) and desorption (r=0.733, p<0.001) diffusion coefficients (obtained using Fick's law of diffusion) with temperature in the second cycle. SIGNIFICANCE: High temperatures increased water sorption of simplified adhesives. Such water sorption may contribute to the failure of resin-dentin bonds.

Transdentinal cytotoxicity and macrophage phenotype of a novel quaternary ammonium silane cavity disinfectant.

OBJECTIVE: To evaluate the transdentinal cytotoxicity and macrophage phenotype response to a novel quaternary ammonium silane (QAS) cavity disinfectant. METHODS: NIH 3T3 mouse fibroblasts were cultured in Dulbecco's Modified Eagle's Medium and incubated for 3 days. The cells (3×104) were seeded on the pulpal side of dentine discs and the occlusal side of the discs were treated with different cavity disinfectants: Group 1: de-ionized water (control); Group 2: 2% chlorhexidine (CHX); Group 3: 2% QAS; Group 4: 5% QAS, and Group 5: 10% QAS. Cell morphology of NIH 3T3 cells was examined using scanning electron microscopy (SEM) and cell viability was assessed using Trypan blue assay. The eluates were collected and applied on cells seeded in 24-well plates. The total protein production, alkaline phosphatase activity and deposition of mineralized nodules were evaluated after 7 and 14 days. Immunofluorescence staining was performed on the samples with primary antibodies of CD68+, CD80+, and CD163+ assessing the macrophage M1/M2 phenotypes. The macrophages were imaged using a confocal scanning light microscope with an excitation wavelength of 488nm. RESULTS: No significant difference in cell viability (p<0.0001), total protein production (p<0.01) and mineralized nodule production (p<0.05) was found between 2% QAS and the control, which was significantly higher than 2% CHX, 5% and 10% QAS after 14 days. Alkaline phosphatase production of 2% QAS was significantly lower than the control (p<0.001), but higher than 2% CHX at 14 days. The M1/M2 macrophage ratio was also significantly lower in the 2% and 10% QAS groups (p<0.05) compared to the control and 2% CHX groups. SIGNIFICANCE: The 2% QAS cavity disinfectant does not have cytotoxic effects on 3T3 NIH mouse fibroblast cells and the predominance of the anti-inflammatory phenotype after its application may stimulate healing and tissue repair.

Changes in resin-infiltrated dentin stiffness after water storage.

Plasticization of polymers by water sorption lowers their mechanical properties in a manner that is predictable by the polarity of their component resins. This study tested the hypothesis that when adhesive resins were used to create resin-infiltrated dentin, the reductions in their flexural moduli after water storage would be lowered proportional to their hydrophilic characteristics. Three increasingly hydrophilic resin blends were used to fabricate polymer beams and macro-hybrid layer models of resin-infiltrated dentin for testing with a miniature three-point flexure device, before and after 1-4 weeks of water storage. Flexural modulus reductions in macro-hybrid layers were related to, and more extensive than, reductions in the corresponding polymer beams. Macro-hybrid layers that were more hydrophilic exhibited higher percent reductions in flexural modulus, with the rate of reduction proportional to the Hoy's solubility parameters for total intermolecular attraction forces (delta(t)) and polar forces (delta(p)) of the macro-hybrid layers.

Chlorhexidine release and water sorption characteristics of chlorhexidine-incorporated hydrophobic/hydrophilic resins.

OBJECTIVES: The aim of this study was to evaluate chlorhexidine release from unfilled non-solvated methacrylate-based resins of increasing hydrophilicity and to examine relationships among Hoy's solubility parameters, water sorption, solubility and the rate of chlorhexidine release. METHODS: Resin discs were prepared from light-cured, experimental resin blends (R1, R2, R3, R4 and R5) containing 0.0, 0.2, 1.0 and 2.0 wt.% chlorhexidine diacetate (CDA). Discs were immersed in distilled water at 37 degrees C, and mass changes were recorded at different periods. Spectral measurements were made to follow change in optical densities of storage solution to examine chlorhexidine release kinetics. After a 28-day period, water sorption, solubility, and the cumulative chlorhexidine release were obtained. Additionally, antibacterial study was performed by observing the presence of inhibition zone against Streptococcus mutans. RESULTS: The most hydrophilic resin (R5) exhibited the highest chlorhexidine release rate. The most hydrophobic resin (R1) exhibited the lowest rate. However, no inhibition zone was produced by any specimens stored in water for 2 weeks. The addition of CDA increased solubility significantly but had no effect on water sorption. Significant positive correlations were seen between water sorption and the cumulative chlorhexidine release. SIGNIFICANCE: Chlorhexidine release from resins may be related to water-induced swelling, which in turn is enhanced by the hydrophilicity of cured polymer matrix.

Effect of proanthocyanidin on ultrastructure and mineralization of dentine collagen.

OBJECTIVE: Proanthocyanidin (PA) is a natural collagen cross-linker that has been used in dentine matrix biomodification for reparative and preventive therapies. This study evaluated the ultrastructure of collagen after its interaction with PA. Furthermore, the mineralization of PA-biomodified collagen matrix was observed. METHODS: Ten freshly extracted sound human molars were sectioned into 0.5mm×1.7mm×7mm beams for ultrastructural evaluation of PA and dentine matrix under Field Emission Scanning Electron Microscopy (FESEM) and Transmission Electron Microscopy (TEM). Specimens for TEM were completely demineralized and divided into three groups according to PA treatments: deionized water, 2% PA and 6.5% PA. The specimens were fixed, dehydrated, sectioned and examined using TEM. Specimens for FESEM were lightly conditioned with EDTA and similarly divided into the three groups for observation using FESEM. Type I collagen from calf skin was used to analyse the mineral interaction after treatment with 6.5% PA. Formvar- and carbon-coated 400-mesh Ni grids (EMS, Hatfiels, PA, USA) were placed over a 2mg/mL collagen solution prepared from calf skin-derived Type I collagen to achieve self-assembly of collagen fibrils. Grids were treated with 6.5% PA and divided into two groups. One group was floated over a remineralization solution containing 20mM HEPES, 2.25mM CaCl2-2H2O, 1.35mM KH2PO4, 3.08mM NaN3 and 130mM KCl and the other group was over a CPP-ACP solution (Tooth mousse 1:100 dilution with deionized water). The floating samples were kept in a 37°C and 100% humidity chamber. Grids were taken out at selected time durations (24h, 48h and 72h for mineralization solution/24h for CPP-ACP) and observed under TEM without staining. Selected area electron diffractions (SAEDs) were performed at 110kV. RESULTS: Following treatment of demineralized dentine collagen matrix with PA, the size and number of interfibrillar spaces were reduced. The collagen fibrils aggregated together with a reduction in porosity. A characteristic banding pattern of collagen fibrils was observed under TEM. Treatment of PA-biomodified collagen fibrils with remineralization solution increased mineral aggregation along its long axis, when compared to the control group. Furthermore, treatment of PA-biomodified collagen fibrils with CPP-ACP solution enhanced mineral uptake and deposition as well as initiated apatite formation within 24h. CONCLUSION: Proanthocyanidin alters the ultrastructure of demineralized dentine collagen matrix. The PA-biomodified collagen matrix promotes remineralization.

Effect of a novel quaternary ammonium silane on dentin protease activities.

OBJECTIVES: Demineralized dentin collagen release C-terminal cross-linked telopeptide (ICTP) and C-terminal peptide (CTX) during degradation. The present study evaluated the effects of dentin pre-treatment with K21, a quaternary ammonium silane (QAS), on matrix metalloproteinase (MMP) and cathepsin K-mediated collagen degradation. METHODS: Dentin beams were demineralized with 10% H3PO4 for 24h. After baseline dry mass measurements, the beams were divided into 5 groups (N=10) according to protease inhibitors. The beams were pre-treated for 2min with 2% chlorhexidine (CHX), 2%, 5% or 10% QAS; no pre-treatment was performed for the control group. The beams were subsequently incubated in calcium- and zinc-containing medium for 3, 7 or 14days, after which changes in dry mass were measured and incubation media were examined for ICTP and CTX release. The MMP-2 and cathepsin K activities in QAS-treated dentin powder were also quantified using ELISA. RESULTS: The two factors (disinfectants and time) had a significant effect on dry mass loss, ICTP and CTX release (p<0.001). The percentage of dry mass loss increased with time and was significantly lower in all experimental groups when compared to the control at 14days (p<0.001). Conversely, the rate of ICTP and CTX release was significantly lower in the experimental groups, compared to the uninhibited control at 7 and 14days (p<0.001). Dentinal MMP-2 and cathepsin K activities were significantly reduced after demineralized dentin was pre-treated with QAS. CONCLUSION: The experimental QAS is a good inhibitor of MMP and cathepsin K activities in demineralized dentin. CLINICAL SIGNIFICANCE: The newly developed antibacterial quaternary ammonium silane increases the resistance of dentin collagen to degradation by inhibiting endogenous matrix metalloproteinases and cysteine cathepsins. The quaternary ammonium silane cavity disinfectant is promising for use as a protease inhibitor to improve durability of resin-dentin bonds.

Effect of a novel quaternary ammonium silane cavity disinfectant on durability of resin-dentine bond.

OBJECTIVE: The present study examined the effect of a quaternary ammonium silane (QAS) cavity disinfectant on the viability of human dental pulp cells, dentine bond durability and nanoleakage of simplified etch-and-rinse adhesives. METHODS: Etched dentine surface of third molars were randomly divided into two adhesive groups, Adper™ Single Bond 2 and Prime & Bond® NT™. For each adhesive, the teeth were randomly assigned to five cavity disinfectant groups (N=6): Group 1: deionised water (control); Group 2: 2% chlorhexidine (CHX); Group 3: 2% QAS; Group 4: 5% QAS and Group 5: 10% QAS. The cavity disinfectants were applied on etched dentine surfaces for 20s, followed by adhesive application. The bonded teeth were sectioned for bond strength testing at 24h, 6 months and 12 months. Viability of human dental pulpal cells was examined using MTT assay. Bond strength data were analysed using 3-way ANOVA and Tukey test. Interfacial nanoleakage was evaluated after 24h and 12 months and analysed using Kruskal-Wallis test. RESULTS: Significant differences in bond strength were observed for the factors disinfectants (p<0.001) and time (p<0.001); while the factor, adhesive, was not significantly different (p=0.203). The 2% QAS cavity disinfectant preserved bond strength of both adhesives and reduced interfacial nanoleakage after 12 months. Cell viability was the lowest for 2% CHX, followed by 2% QAS and the control. CONCLUSIONS: The 2% QAS cavity disinfectant demonstrated greater cell viability compared to 2% CHX, with no adverse effect on immediate bond strength and preserved bond stability over time. CLINICAL SIGNIFICANCE: Incorporation of 2% quaternary ammonium silane cavity disinfectant in the resin-dentine bonding protocol enhances the success rate of bonded restorations.

Incompatibility of oxalate desensitizers with acidic, fluoride-containing total-etch adhesives.

The use of oxalate desensitizers on acid-etched dentin prior to adhesive application can result in subsurface tubular occlusion by calcium oxalate crystals. However, the solubility of calcium oxalate increases in acidic solution. We hypothesized that total-etch adhesives can, depending upon their pH, interact with oxalate-desensitizer-treated dentin in an adverse manner. Acid-etched human dentin treated with 2 oxalate desensitizers (BisBlock and Super Seal) was bonded with 4 simplified total-etch adhesives: One-Step (OS), Single Bond (SB), OptiBond Solo Plus (OB), and Prime&Bond NT (PB). Composite-dentin beams were examined by SEM and TEM, both of which revealed numerous spherical globules on OB- and PB-bonded, desensitizer-treated dentin, but not in OS or SB samples. Bond strengths produced by OB and PB were significantly lower in oxalate-treated specimens than those produced by OS or SB. These surface globules may have interfered with hybridization of demineralized dentin with OB and PB resins and caused compromised bond strengths.

Systematic Review and Meta-Analysis of Randomized Clinical Trials on Chemomechanical Caries Removal.

OBJECTIVES: The aim of this review was to assess the methodologies used in previously published prospective randomized clinical trials on chemomechanical caries removal and to conduct a meta-analysis to quantify the differences in the excavation time between chemomechanical and conventional caries removal methods. METHODS: An electronic search was performed using Scopus, PubMed, EBSCO host, and Cochrane Library databases. The following categories were excluded during the assessment process: non-English studies published before 2000, animal studies, review articles, laboratory studies, case reports, and nonrandomized or retrospective clinical trials. The methodologies of the selected clinical trials were assessed. Furthermore, the reviewed clinical trials were subjected to meta-analysis for quantifying the differences in excavation time between the chemomechanical and the conventional caries removal techniques. RESULTS: Only 19 randomized clinical trials fit the inclusion criteria of this systematic review. None of the 19 reviewed trials completely fulfilled Delphi's ideal criteria for quality assessment of randomized clinical trials. The meta-analysis results revealed that the shortest mean excavation time was recorded for rotary caries excavation (2.99±0.001 minutes), followed by the enzyme-based chemomechanical caries removal method (6.36±0.08 minutes) and the the hand excavation method (atraumatic restorative technique; 6.98±0.17 minutes). The longest caries excavation time was recorded for the sodium hypochlorite-based chemomechanical caries removal method (8.12±0.02 minutes). CONCLUSIONS: It was found that none of the current reviewed trials fulfilled all the ideal requirements of clinical trials. Furthermore, the current scientific evidence shows that the sodium hypochlorite-based (Carisolv) chemomechanical caries removal method was more time consuming when compared to the enzyme-based (Papacarie) chemomechanical and the conventional caries removal methods. Further prospective randomized controlled clinical trials evaluating the long-term follow-up of papain-treated permanent teeth are needed.

Effect of resin hydrophilicity and water storage on resin strength.

This study evaluated the change in the ultimate tensile strength (UTS) of five polymerised resin blends of increasing hydrophilicity, after ageing in distilled water or silicon oil. Resin blocks were prepared from each resin blend by dispensing the uncured resin into a flexible, embedding mould, containing multiple cavities. The resins were polymerised in the moulds under nitrogen at 551.6 kPa and light-activated at 125 degrees C for 10 min. After dry ageing for 24 h at 37 degrees C, the middle third of each resin specimen was trimmed into an 'I' shape. Fifteen control specimens were randomly selected from each resin blend for baseline UTS evaluation. The UTS of the experimental specimens were determined after 1, 3, 6 and 12 months of ageing in water or oil. The UTS of each group of resins at different storage periods in water or oil were analysed using the Friedman multiple ANOVA on ranks and Dunn's multiple comparison tests at 95% confidence level. Significant reduction (p < 0.01) in UTS was observed in Groups II-V resins after 12-month storage in water, while the most hydrophobic Group I resin showed no significant change (p > 0.05) in the same period. The percentage reduction in UTS increased with the hydrophilicity of the resin blends. Long-term water storage of hydrophilic resin blends such as those employed in dentine adhesives, resulted in a marked reduction in their mechanical strength that may compromise the durability of resin-dentine bonds.

A nanoleakage perspective on bonding to oxidized dentin.

The mechanism responsible for sodium-hypochlorite-induced reduction in dentin bond strength and its reversal with reducing agents is unknown. This study examined the relationship between nanoleakage and reversal of compromised bonding to oxidized dentin. Acid-etched dentin was completely depleted of demineralized collagen matrix when sodium hypochlorite was used. Specimens were bonded with two single-bottle dentin adhesives. They were immersed in ammoniacal silver nitrate for 24 hrs before being processed for transmission electron microscopy. For both adhesives, tensile bond strengths of acid-etched dentin were significantly reduced after sodium hypochlorite treatment, but were reversed when sodium ascorbate was used. After sodium hypochlorite application, reticular nanoleakge patterns in hybrid layers were replaced by vertical, shag-carpet-like patterns along the demineralization front. This type of nanoleakage was completely eliminated after sodium ascorbate treatment with the materials tested. Residual sodium hypochlorite within the porosities of mineralized dentin may result in incomplete resin polymerization, and hence compromised bond strength.