The effect of casein and calcium containing paste on plaque pH following a subsequent carbohydrate challenge

Objectives

Previous research has shown that regular use of CPP–ACP increases calcium and inorganic phosphates in plaque and reduces enamel mineral loss. The aim of this study was to investigate if a CPP–ACP-containing paste would neutralize acidic challenges in dental plaque following sucrose rinse.

Method

Plaque pH was measured on 15 subjects in a cross-over study with and without prior application of the paste and with and without CPP–ACP. On each occasion, subjects rinsed with 10% sucrose and sorbitol solutions for 2 min in randomized order.

Results

The results showed the median lowest pH without paste was 4.8 (IQR: 4.7–5.0) and with mousse 5.6 (IQR: 5.5–5.6 and p < 0.001). The median lowest pH was 5.0 (IQR: 4.9–5.3) without CPP–ACP and with CPP–ACP was 5.8 (5.6–6.1 and p < 0.001). The time that pH remained below 5.7 and the time to return to resting pH showed similar differences in all subjects (p < 0.01).

Conclusion

The results indicate that prior application of a CPP–ACP-containing paste reduced the fall in plaque pH following a sucrose challenge.     

Intake of dairy products and the prevalence of dental caries in young children

Objectives

In vitro studies show that milk or milk components may have cariostatic properties. However, the results of epidemiological studies on the association between intake of dairy products and dental caries have been inconsistent. The purpose of this cross-sectional study was to examine the association between intake of dairy products and the prevalence of dental caries in young children.

Methods

Study subjects were 2058 Japanese children aged 3 years. Information on diet was assessed with a self-administered brief diet history questionnaire for children. The consumption of dairy products was categorized into 3 levels in order to represent the tertiles as closely as possible. Dental caries was assessed by a visual examination. Adjustment was made for sex, toothbrushing frequency, use of fluoride, between-meal snack frequency, maternal smoking during pregnancy, environmental tobacco smoke exposure at home, and paternal and maternal educational levels.

Results

Compared with yogurt consumption at the lowest tertile (<1 time/week), its intake at the highest level (≥4 times/week) was significantly associated with a lower prevalence of dental caries, showing a clear dose–response relationship (adjusted prevalence ratio = 0.78, 95% confidence interval: 0.62–0.98, P for trend = 0.04). There were no material associations between intake of cheese, bread and butter, or milk and the prevalence of dental caries.

Conclusions

These data suggest that a high consumption of yogurt may be associated with a lower prevalence of dental caries in young children.     

The effect of sucrose on plaque and saliva urease levels in vivo

Objective

Dietary sugar exposures induce an immediate drop of the plaque pH. Based on in vitro observations, it was hypothesized that oral bacteria may rapidly respond to this environmental change by increasing the activity or expression of alkali-generating pathways, such as the urease pathway. The objective of this exploratory in vivo study was to determine the short-term effect of a brief sucrose exposure on plaque and saliva urease activity and expression, and to relate this effect to caries experience.

Methods

Urease activity levels were measured in plaque and saliva samples collected from 20 children during fasting conditions and 30 min after rinsing with a sucrose solution. Streptococcus salivarius ureC-specific mRNA in saliva was quantified using real-time RT-PCR. The impact of host-related factors, such as age, gender, sugar consumption, salivary mutans streptococci levels and caries status on urease activity was evaluated.

Results

Plaque urease activity under fasting conditions was higher in subjects with low caries and mutans streptococci levels. This difference was not observed after the sucrose exposure. The response of urease to sucrose in vivo did not depend on caries experience or salivary mutans levels. Significant increase in urease activity of plaque and saliva after exposure to sucrose was observed only in the subjects who had low urease levels at baseline.

Conclusions

The findings of this exploratory study suggest that plaque urease activity may have an important long-term influence in caries development but not during a cariogenic challenge.     

Effects of xylitol mouthrinse on Streptococcus mutans

Objectives

This study aimed to measure the effect of xylitol mouthrinse on salivary Streptococcus mutans counts.

Methods

Subjects in the study group (n = 25) used xylitol mouthrinse for 4 weeks, while another group (n = 25) used saccharine mouthrinse. S. mutans were measured before and after intervention.

Results

At the baseline the mean S. mutans scores were 3.9 (SE = 0.03) and 3.9 (0.04) for the xylitol group and control group respectively, while the scores were 2.8 (0.13) and 3.9 (0.07) after the intervention. Significant reductions (p < 0.01) in the scores of S. mutans were found after the four week use of xylitol mouthrinse.

Conclusions

Significant reductions in the scores of S. mutans were found after the four week use of 20% xylitol mouthrinse. The bacteriostatic effect of xylitol mouthrinse on S. mutans may be comparable to other xylitol products. Further studies are needed to confirm both the short and long term effects of xylitol mouthrinse.     

Relationship among microbiological composition and presence of dental plaque, sugar exposure, social factors and different stages of early childhood caries

Objective

This cross-sectional study aimed to investigate the relationship among microbiological composition of dental plaque, sugar exposure and social factors, as well as the presence of visible plaque in preschoolers with different stages of early childhood caries.

Design

A total of 169 children were clinically examined according to the World Health Organisation criteria + early caries lesions and were divided into three groups: caries-free (n = 53), early caries lesions-ECL (n = 56), and cavitated caries lesions-CCL (n = 60). The presence of clinically visible dental plaque on maxillary incisors was recorded. After that, dental plaque from all buccal and lingual smooth surfaces was collected and the number of colony-forming units of mutans streptococci and total microorganism, as well as the presence of lactobacilli was determined. Daily frequency of meals containing sugar was assessed by a diet chart whereas social factors were evaluated by a questionnaire. The data were analysed by chi-square test followed by multiple logistic regressions (α = 0.05, confidence interval = 95%).

Results

High levels of mutans streptococci (OR = 2.28), high total sugar exposure (OR = 5.45) and presence of dental plaque (OR = 2.60) showed significant association with ECL (p < 0.05). High total microorganism count (OR = 5.18), high solid sugar exposure (OR = 2.50) and the presence of lactobacilli (OR = 24.99) revealed significant association with CCL (p < 0.05).

Conclusions

These results support the conclusion that dietary sugar experience influenced the microbiological composition of dental plaque. Moreover, the early stage of caries is highly affected by mutans streptococci and visible dental plaque on maxillary incisors whereas cavities are strongly related to lactobacilli and total microorganism.     

Dynamics of oral microbial community profiling during severe early childhood caries development monitored by PCR-DGGE

Objective

To monitor the longitudinal changes in oral microbial diversity of children with severe early childhood caries (S-ECC) compared to caries free (CF) controls.

Methods

Dental plaque samples of 12 children in each group at 8, 14, 20, 26 and 32 months of age were analysed. Total microbial genomic DNA was isolated from each sample, and PCR-denaturing gradient gel electrophoresis (DGGE) analyses were carried out.

Results

The number of bands was significantly higher in the CF group (18.17 ± 4.91 bands) than in the S-ECC group (14.54 ± 5.56 bands) at 32 months of age (P < 0.05). A total of 21 genera were identified in all subjects, and there were no significant differences between the two groups at genus level. DGGE profiles showed that most of the clusters were constructed from one individual over time in the both groups.

Conclusions

The onset of S-ECC is accompanied by a decrease in microbial diversity. The overall composition of the microbiota is highly similar within an individual over time.     

A New “Silver-Bullet” to treat caries in children – Nano Silver Fluoride: A randomised clinical trial

Background

Untreated dental caries in children remains a public health challenge in poor communities.

Objectives

This prospective controlled clinical trial investigated the effectiveness of a new anti-caries agent, Nano Silver Fluoride (NSF), applied once a year to arrest caries in children.

Methods

One hundred thirty decayed primary teeth were randomly divided into two groups: NSF as the experimental agent and water as the control group. Teeth were clinically diagnosed and treated by one masked examiner and followed up at seven days and five and 12 months by another calibrated examiner who was blinded to the type of treatment. The criteria of the ICDAS II were followed to determine the activity of lesion and the diagnosis of caries. The Pearson's chi-square test was used to compare the groups during different follow-up exams.

Results

At seven days, 81% of teeth in the NSF group exhibited arrested caries, whereas in controls, no teeth had arrested decay (p < 0.001) [PF, prevented fraction = 81%]. After five months, the NSF group had 72.7% with arrested decay, and the control group had 27.4% (p < 0.001) [PF = 62.5%]. At 12 months, 66.7% of the lesions treated with NSF were still arrested, while the control group had 34.7% remaining arrested (p = 0.003) [PF = 50%]. The number need to treat (NNT) at five months was two, and at 12 months, the number was three.Clinical Signi?cance: The NSF formulation is effective to arrest active dentine caries and not stain teeth.

Conclusions

NSF was demonstrated to be effective in arresting caries in children in poor communities.     

The influence of different restorative materials on secondary caries development in situ

Objectives

The effect of direct restorative materials on caries lesion formation was investigated with an 8-week in situ study with split-mouth design, testing the hypothesis that no difference in mineral loss next to a restoration would be found between different composite-based-materials and amalgam.

Methods

Six groups (n = 18) of restored dentine samples were prepared using amalgam, a microhybrid, a nanohybrid and a silorane composite. The composites were adhesively bonded with systems with or without an antibacterial monomer (Clearfil-SE-Protect, Clearfil-SE-bond, respectively), except for the silorane group (Silorane-System-Adhesive). Non-restored dentine samples were used as control (primary caries). Samples were inserted into slots, in lower prosthesis especially made for the experiment. Subjects were instructed to dip the lower prosthesis in a sucrose solution 4 times per day. At baseline and 8 weeks, samples were radiographed extra-orally and the integrated mineral loss was calculated. Data were statistically analyzed using multiple linear regression with a multilevel model (p = 0.05).

Results

Nine subjects were selected, and only outer lesions were observed. The hypothesis was partially rejected, as the microhybrid composite bonded with the antibacterial system and the nanohybrid composite presented statistically significant lower mineral loss compared to amalgam. Also, no significant differences were seen for these groups compared to control.

Conclusion

Within the limits of this study, the restorative material may influence outer lesion progression. Amalgam was not found to be related to lower secondary caries progression in dentine compared to composite-based materials after 8 weeks in situ.

Clinical Significance

Although patient factors play a major role in caries progression, the restorative material may affect outer secondary lesion progression.     

Association of DLX3 gene polymorphism and dental caries susceptibility in Japanese children

Objective

In this study, we investigated whether single nucleotide polymorphisms (SNPs) in DLX3 are associated with dental caries susceptibility in Japanese children.

Design

Genomic DNA of 201 Japanese children was extracted from buccal epithelial cells. The subjects were divided into two groups: ‘low level’ group with <10,000 colony forming units (CFU) of Streptococcus mutans/mL saliva (level 0) and ‘high level’ group with ≥10,000 CFU/mL (more than level 1). Each group was further divided according to decayed, missing, filled teeth (dmft) into low caries experience (dmft ≤ 2) and high caries experience (dmft ≥ 3). Seven SNPs in DLX3 were genotyped using TaqMan^® SNP Genotyping Assay.

Results

Statistical significant association was observed between DLX3 (rs2278163) and caries experience in ‘high level Mutans streptococci’ group.

Conclusion

These findings suggest that rs2278163 SNP of DLX3 might be associated with dental caries susceptibility in Japanese children. T and C alleles of rs2278163 SNP may potentially be involved in caries susceptibility and caries protection respectively.     

Sugar-sweetened beverages and dental caries in adults: A 4-year prospective study

Objectives

To explore the association between frequency of consumption of sugar-sweetened beverages (SSB) and caries increment over 4 years in adults. A second objective was to explore whether the association between frequency of SSB consumption and caries increment varied by socio-demographic characteristics and use of fluoride toothpaste.

Methods

Data from 939 dentate adults who participated in both the Health 2000 Survey and the Follow-Up Study of Finnish Adults’ Oral Health were analysed. At baseline, participants provided information on demographic characteristics, education and dental behaviours, including two questions on frequency of SSB consumption. The 4-year net DMFT increment was calculated using data from baseline and follow-up clinical oral examinations. The association was tested in negative binomial regression models and the moderating role of sex, age, education and use of fluoride toothpaste was examined by adding their two-way interaction with SSB consumption to the main effects model.

Results

A positive association was found between frequency of SBS consumption and 4-year net DMFT increment, regardless of participants’ socio-demographic and behavioural characteristics. Adults drinking 1–2 and 3+ SSB daily had, respectively, 31% (Incidence Rate Ratio: 1.31; 95%CI: 1.02–1.67) and 33% (IRR: 1.33; 95%CI; 1.03–1.72) greater net DMFT increments than those not drinking any SSB. None of the four two-way interaction terms was significant (all p > 0.05).

Conclusion

There seems to be a dose–response relationship between frequency of SSB consumption and caries increment in adults. That association was consistent across socio-demographic characteristics, and more importantly, use of fluoride toothpaste.

Clinical significance

Drinking sugar-sweetened beverages on a daily basis is related to greater caries risk in adults.     

Relationship between daily habits, Streptococcus mutans, and caries among schoolboys

Objectives

The purpose of this study was to examine the associations between daily habits, Streptococcus mutans, and caries using International Caries Detection and Assessment System Caries Index (ICDAS CI); and compare it to the DMF index.

Subjects and methods

Altogether 122 children were examined and interviewed. Saliva and plaque samples were collected and analyzed by Dentocult SM^® Strip Mutans test. ICDAS CI was calculated by counting all ICDAS caries scores of all surfaces divided by total number of carious teeth.

Results

ICDAS CI was significantly (p < 0.01) and strongly associated with DMFT/dmft (ρ = 0.72), DMFS/dmfs (ρ = 0.72), total number of carious teeth (DT/dt) (ρ = 0.77), enamel caries surfaces (ρ = 0.61) and dentine caries surfaces (ρ = 0.75). Plaque S. mutans was significantly (p < 0.05) correlated with ICDAS CI and DT/dt. Children who brushed once a day or more had significantly lower ICDAS CI (p < 0.01). Children who consumed sweets or drank soft drinks more than once a day had significantly higher ICDAS CI (p < 0.05). No significant association was found between ICDAS CI and frequency of flossing, use of mouthrinse, or gum chewing.

Conclusion

ICDAS CI seems to have similar trends as DMF indices, but includes more information about the stage, severity, and progress of the caries lesions of the patient.     

Quantitative light-induced fluorescence (QLF): A tool for early occlusal dental caries detection and supporting decision making in vivo

Objectives

This study reports the development and assessment of a novel method using quantitative light-induced fluorescence (QLF), to determine whether QLF parameters ΔF and ΔQ were appropriate for aiding diagnosis and clinical decision making of early occlusal mineral loss by comparing QLF analysis with actual restorative management.

Methods

Following ethical approval, 46 subjects attending a dental teaching hospital were enrolled. White light digital (WL) and QLF images/analyses of 46 unrestored posterior teeth with suspected occlusal caries were made after a clinical decision had already been taken to explore fissures operatively. WL and QLF imaging/analysis were repeated after initial cavity preparation. The type of restorative treatment was determined by the supervising clinician independent of any imaging performed. Actual restorative management carried out was recorded as fissure sealant/preventive resin restoration (F/P) or class I occlusal restoration (Rest.) thus reflecting the extent of intervention (=gold standard). All QLF images were analysed independently.

Results

The results showed statistically significant differences between the two treatment groups ΔF (p = 0.002) (mean 22.60 – F/P and 28.80 – Rest.) and ΔQ (p = 0.012) (mean 230.49 – F/P and 348.30 – Rest.).

Conclusions

ΔF and ΔQ values may be useful in aiding clinical diagnosis and decision making in relation to the management of early mineral loss and restorative intervention of occlusal caries.

Clinical significance

QLF has the potential to be a valuable tool for caries diagnosis in clinical practice.     

Comparison of Knoop and Vickers surface microhardness and transverse microradiography for the study of early caries lesion formation in human and bovine enamel

Objective

The aims of the present laboratory study were twofold: a) to investigate the suitability of Knoop and Vickers surface microhardness (SMH) in comparison to transverse microradiography (TMR) to investigate early enamel caries lesion formation; b) to compare the kinetics of caries lesion initiation and progression between human and bovine enamel.

Design

Specimens (90 × bovine and 90 × human enamel) were divided into six groups (demineralization times of 8/16/24/32/40/48 h) of 15 per enamel type and demineralized using a partially saturated lactic acid solution. SMH was measured before and after demineralization and changes in indentation length (ΔIL) calculated. Lesions were characterized using TMR. Data were analyzed (two-way ANOVA) and Pearson correlation coefficients calculated.

Results

ΔIL increased with increasing demineralization times but plateaued after 40 h, whereas lesion depth (L) and integrated mineral loss (ΔZ) increased almost linearly throughout. No differences between Knoop and Vickers SMH in their ability to measure enamel demineralization were observed as both correlated strongly. Overall, ΔIL correlated strongly with ΔZ and L but only moderately with the degree of surface zone mineralization, whereas ΔZ and L correlated strongly. Bovine demineralized faster than human enamel (all techniques).

Conclusions

Lesions in bovine formed faster than in human enamel, although the resulting lesions were almost indistinguishable in their mineral distribution characteristics. Early caries lesion demineralization can be sufficiently studied by SMH, but its limitations on the assessment of the mineral status of more demineralized lesions must be considered. Ideally, complementary techniques to assess changes in both physical and chemical lesion characteristics would be employed.     

A comparison of root caries diagnosis based on visual-tactile criteria and DIAGNOdent in vivo

Objectives

This clinical study aimed to evaluate the validity of using DIAGNOdent in diagnosing root caries, and to assess the sensitivity and specificity of different cut-off DIAGNOdent values in assessing root caries with reference to visual-tactile criteria.

Methods

Exposed root surfaces were assessed by one examiner for root caries on 266 subjects using visual-tactile criteria and DIAGNOdent 2095 after dental scaling. Associations between DIAGNOdent values and visual-tactile diagnosis of root caries were determined. The cut-off level for statistical significance was 0.05. The sensitivity and specificity of DIAGNOdent with difference cut-off points were analysed compared to visual-tactile diagnosis of root caries.

Results

There was significant difference between DIAGNOdent values obtained from sound and carious root surfaces (p < 0.001). On carious surfaces, active root caries obtained significantly higher DIAGNOdent values than inactive root caries (p < 0.001). With increasing cut-off point DIAGNOdent values from 5 to 35, sensitivity decreased from 91.4% to 16.2% and specificity increased from 64.4% to 98.2%. A cut-off point of DIAGNOdent value between 5 and 10 produced the highest combined sensitivity and specificity.

Conclusions

There was a significant difference in DIAGNOdent values between sound and carious root surfaces diagnosed by visual-tactile criteria supporting the validity of DIAGNOdent for assessing root caries. A DIAGNOdent value between 5 and 10 produced the highest combined sensitivity and specificity when visual-tactile assessment of root caries was regarded as the criterion. These findings have implications in using and explaining DIAGNOdent values in assessing root caries.     

Caries-preventive effectiveness of fluoride varnish as adjunct to oral health promotion and supervised tooth brushing in preschool children: A double-blind randomized controlled trial

Objectives

To evaluate the effect of biannual fluoride varnish applications in preschool children as an adjunct to school-based oral health promotion and supervised tooth brushing with 1000 ppm fluoride toothpaste.

Methods

424 preschool children, 2–5 year of age, from 10 different pre schools in Athens were invited to this double-blind randomized controlled trial and 328 children completed the 2-year programme. All children received oral health education with hygiene instructions twice yearly and attended supervised tooth brushing once daily. The test group was treated with fluoride varnish (0.9% diflurosilane) biannually while the control group had placebo applications. The primary endpoints were caries prevalence and increment; secondary outcomes were gingival health, mutans streptococci growth and salivary buffer capacity.

Results

The groups were balanced at baseline and no significant differences in caries prevalence or increment were displayed between the groups after 1 and 2 years, respectively. There was a reduced number of new pre-cavitated enamel lesions during the second year of the study (p = 0.05) but the decrease was not statistically significant. The secondary endpoints were unaffected by the varnish treatments.

Conclusions

Under the present conditions, biannual fluoride varnish applications in preschool children did not show significant caries-preventive benefits when provided as an adjunct to school-based supervised tooth brushing with 1000 ppm fluoride toothpaste.

Clinical significance

In community based, caries prevention programmes, for high caries risk preschool children, a fluoride varnish may add little to caries prevention, when 1000 ppm fluoride toothpaste is used daily.     

Effect of chlorhexidine-thymol varnish on root caries in a geriatric population: A randomized double-blind clinical trial

Objectives

Little is known about the effect of Cervitec^®, a chlorhexidine-thymol varnish, on root caries. Our objective was to determine whether a 3-monthly application of Cervitec^® over 1 year would limit the progress of existing root caries lesions and reduce the incidence of dental root caries in a group of dentate institutionalized elderly, as a complement to their usual oral hygiene practices.

Methods

A double-blind randomized clinical trial was conducted in 68 subjects (34 per group) in two residences in Almería (Spain). Twenty-one subjects with 60 root caries lesions and 25 with 65 lesions, in the Cervitec^® and placebo groups, respectively, completed the study. Varnishes were applied twice in the first week, 1 month later, and every 3 months until the end of the study. Clinical parameters associated with established lesions were determined at baseline and after 6 and 12 months, as was the incidence of root caries lesions.

Results

The clinical evolution of lesions was significantly better in the Cervitec^® group as opposed to the placebo group in terms of width, height, color, and texture. The increase in root caries was significantly lower (p = 0.039) in the Cervitec^® group.

Conclusion

According to these results, Cervitec^® may help to control established root lesions and reduce the incidence of root caries lesion among institutionalized elderly.     

Novel protein-repellent dental adhesive containing 2-methacryloyloxyethyl phosphorylcholine

Objectives

Biofilms at tooth-restoration margins can produce acids and cause secondary caries. A protein-repellent adhesive resin can potentially inhibit bacteria attachment and biofilm growth. However, there has been no report on protein-repellent dental resins. The objectives of this study were to develop a protein-repellent bonding agent incorporating 2-methacryloyloxyethyl phosphorylcholine (MPC), and to investigate its resistance to protein adsorption and biofilm growth for the first time.

Methods

MPC was incorporated into Scotchbond Multi-Purpose (SBMP) at 0%, 3.75%, 7.5%, 11.25%, and 15% by mass. Extracted human teeth were used to measure dentine shear bond strengths. Protein adsorption onto resins was determined by a micro bicinchoninic acid (BCA) method. A dental plaque microcosm biofilm model with human saliva as inoculum was used to measure biofilm metabolic activity and colony-forming unit (CFU) counts.

Results

Adding 7.5% MPC into primer and adhesive did not decrease the dentine bond strength, compared to control (p > 0.1). Incorporation of 7.5% of MPC achieved the lowest protein adsorption, which was 20-fold less than that of control. Incorporation of 7.5% of MPC greatly reduced bacterial adhesion, yielding biofilm total microorganism, total streptococci, and mutans streptococci CFU that were an order of magnitude less than control.

Conclusions

A protein-repellent dental adhesive resin was developed for the first time. Incorporation of MPC into primer and adhesive at 7.5% by mass greatly reduced the protein adsorption and bacterial adhesion, without compromising the dentine bond strength.

Clinical significance

The novel protein-repellent primer and adhesive are promising to inhibit biofilm formation and acid production, to protect the tooth-restoration margins and prevent secondary caries.     

Clinical comparison of a flowable composite and fissure sealant: A 24-month split-mouth,randomized, and controlled study

Objectives

The aim of this clinical study was to evaluate the retention rate and caries-prevention effect of a flowable composite compared to a conventional resin-based sealant in a young population over a 24-month period.

Methods

Thirty-four patients, ranging in age from 16 to 22 years, diagnosed with at least 2 non-cavitated pit-and-fissure caries in the first and second molars were selected for this randomized split-mouth design trial. A total of 220 sealants, were placed in 117 upper molars and 103 lower molars. The teeth were sealed with a flowable resin composite (Tetric Evo Flow) or a sealant material (Helioseal F). Each restoration was independently evaluated in terms of retention and the presence of caries at baseline and at 1, 6, 12, and 24 months. Data were analyzed using non-parametric Mann–Whitney U and Friedman 1-way ANOVA tests at p < 0.05.

Results

Tetric Evo Flow showed complete retention with 100%, 95.5%, 93.8%, and 88.5% at 1, 6, 12, and 24-month evaluations, respectively, while Helioseal F retention rates were 98.1%, 95.5%, 94.8%, and 85.4%, respectively, for the same evaluation periods. At the 24-month recall, 4 (4.2%) total losses were observed in subjects treated with Tetric Evo Flow and 2 total losses (2.1%) for Helioseal F, respectively. No significant differences were observed between the materials in retention rates or caries incidence for each evaluation period (p > 0.05).

Conclusion

Placement of flowable composite as fissure sealants in the younger population seems to be as effective as conventional fluoride containing fissure sealants for the prevention of fissure caries.

Clinical relevance

The use of a flowable composite as a fissure sealant material, in conjunction with a total-etch, single bottle adhesive, yielded better retention than did the conventional fluoride containing resin-based fissure sealant over a 24-month period in young patients.     

Dental plaque microcosm response to bonding agents containing quaternary ammonium methacrylates with different chain lengths and charge densities

Objectives

Antibacterial bonding agents are promising to combat bacteria and caries at tooth-restoration margins. The objectives of this study were to incorporate new quaternary ammonium methacrylates (QAMs) to bonding agent and determine the effects of alkyl chain length (CL) and quaternary amine charge density on dental plaque microcosm bacteria response for the first time.

Methods

Six QAMs were synthesized with CL = 3, 6, 9, 12, 16, 18. Each QAM was incorporated into Scotchbond multi-purpose (SBMP). To determine the charge density effect, dimethylaminododecyl methacrylate (DMAHDM, CL = 16) was mixed into SBMP at mass fraction = 0%, 2.5%, 5%, 7.5%, 10%. Charge density was measured using a fluorescein dye method. Dental plaque microcosm using saliva from ten donors was tested. Bacteria were inoculated on resins. Early-attachment was tested at 4 h. Biofilm colony-forming units (CFU) were measured at 2 days.

Results

Incorporating QAMs into SBMP reduced bacteria early-attachment. Microcosm biofilm CFU for CL = 16 was 4 log lower than SBMP control. Charge density of bonding agent increased with DMAHDM content. Bacteria early-attachment decreased with increasing charge density. Biofilm CFU at 10% DMAHDM was reduced by 4 log. The killing effect was similarly-strong against total microorganisms, total streptococci, and mutans streptococci.

Conclusions

Increasing alkyl chain length and charge density of bonding agent was shown for the first time to decrease microcosm bacteria attachment and reduce biofilm CFU by 4 orders of magnitude. Novel antibacterial resins with tailored chain length and charge density are promising for wide applications in bonding, cements, sealants and composites to inhibit biofilms and caries.     

Micro-hardness and mineral loss of enamel lesions after infiltration with various resins: Influence of infiltrant composition and application frequency in vitro

Objectives

The aim of this in vitro study was to evaluate the influence of infiltrant composition and application frequency on micro-hardness and lesion progression after resin infiltration of artificial enamel lesions.

Methods

In each of 100 bovine enamel samples, three artificial caries lesions were created (pH = 4.95, 50 days). After etching two of the lesions (37% phosphoric acid) specimens were randomly allocated to five infiltrants (four experimental infiltrants with different monomer and solvent compositions and penetration coefficients, and one commercial infiltrant [Icon, DMG]). Lesions were then infiltrated and light-cured, and infiltration repeated afterwards for one of the lesions. Infiltrated samples were cut into halves, with one half being demineralised for further 50 days. Micro-hardness (VHN) and integrated mineral loss (ΔZ) were evaluated at baseline and after second demineralisation. Repeated measures ANOVA and paired t-tests were used to analyse influence of material composition and application frequency on micro-hardness and lesion progression (integrated mineral loss difference ΔΔZ).

Results

Resin infiltration significantly increased micro-hardness and reduced lesion progression compared to untreated artificial lesions (p < 0.05, t-test). Neither micro-hardness nor lesion progression were significantly influenced by material composition (p > 0.05, ANOVA). In contrast, twice application resulted in significantly increased micro-hardness and demineralisation resistance of infiltrated lesions (p < 0.05, ANOVA).

Conclusion

Resin infiltration significantly improves micro-hardness and demineralisation resistance of enamel lesions; these effects are significantly enhanced if resins are applied twice. Experimental resins did not outperform the commercial infiltrant.

Clinical significance

This in vitro study demonstrated that resin infiltration significantly increases both micro-hardness and demineralisation resistance of enamel caries lesions. Twice application of the infiltrant seems to increase these effects. In contrast, the composition of the infiltrant had no significant influence on investigated parameters.