Clinical and microbiological performance of resin-modified glass-ionomer liners after incomplete dentine caries removal

Evaluating antimicrobial activity and cytotoxicity of silver nanoparticles incorporated into reinforced zinc oxide eugenol: an in vitro study

PURPOSE

This study aimed to evaluate the antibacterial and cytotoxic effects of reinforced zinc oxide-eugenol (rZOE) incorporated with different concentrations of silver nanoparticles (AgNPs).

METHODS

The pastes of rZOE alone or mixed with AgNPs at concentrations of 1%, 2%, and 5% of weight were prepared. In vitro antimicrobial activity of prepared materials against Streptococcus (S.) mutans and Lactobacillus (L.) acidophilus were evaluated after 2, 4, and 6 h of contact times using direct contact test (DCT) and also following 24 h incubation by well-diffusion test (WDT). The cytotoxicity of the tested materials on human dental pulp stem cells was also determined by MTT assay.

RESULTS

The DCT demonstrated that the time-dependent reductions of the colony numbers of both bacteria by three different concentrations of AgNPs incorporated into rZOE were equal but steeper than the rZOE alone (P < 0.05). The increases in growth inhibition zones of S. mutans and L. acidophilus were associated with the increasing concentration of AgNPs mixed with rZOE in the WDT; however, statistical analysis did not show any significant differences (P = 0.092). The MTT assay revealed a significantly lower percentage of cell viability after 1 day of culture only with the rZOE + AgNP5% in comparison to the rZOE alone (P = 0.011) and the control medium (P = 0.001).

CONCLUSION

Since the antimicrobial activities of three different concentrations of AgNPs incorporated into rZOE were equal and AgNPs had lower toxicity at lower concentrations, using AgNPs at 1% concentration is suggested to be mixed with rZOE.

Bioactivity and remineralization potential of modified glass ionomer cement: A systematic review of the impact of calcium and phosphate ion release

This systematic review investigates the effectiveness of calcium and phosphate ions release on the bioactivity and remineralization potential of glass ionomer cement (GIC). Electronic databases, including PubMed-MEDLINE, Scopus, and Web of Science, were systematically searched according to PRISMA guidelines. This review was registered in the PROSPERO database. Five eligible studies on modifying GIC with calcium and phosphate ions were included. The risk of bias was assessed using the RoBDEMAT tool. The incorporation of these ions into GIC enhanced its bioactivity and remineralization properties. It promoted hydroxyapatite formation, which is crucial for remineralization, increased pH and inhibited cariogenic bacteria growth. This finding has implications for the development of more effective dental materials. This can contribute to improved oral health outcomes and the management of dental caries, addressing a prevalent and costly oral health issue. Nevertheless, comprehensive longitudinal investigations are needed to evaluate the clinical efficacy of this GIC's modification.

Current Strategies to Control Recurrent and Residual Caries with Resin Composite Restorations: Operator- and Material-Related Factors

This review addresses the rationale of recurrent and/or residual caries associated with resin composite restorations alongside current strategies and evidence-based recommendations to arrest residual caries and restrain recurrent caries. The PubMed and MEDLINE databases were searched for composite-associated recurrent/residual caries focusing on predisposing factors related to materials and operator’s skills; patient-related factors were out of scope. Recurrent caries and fractures are the main reasons for the failure of resin composites. Recurrent and residual caries are evaluated differently with no exact distinguishment, especially for wall lesions. Recurrent caries correlates to patient factors, the operator’s skills of cavity preparation, and material selection and insertion. Material-related factors are significant. Strong evidence validates the minimally invasive management of deep caries, with concerns regarding residual infected dentin. Promising technologies promote resin composites with antibacterial and remineralizing potentials. Insertion techniques influence adaptation, marginal seal, and proximal contact tightness. A reliable diagnostic method for recurrent or residual caries is urgently required. Ongoing endeavors cannot eliminate recurrent caries or precisely validate residual caries. The operator’s responsibility to precisely diagnose original caries and remaining tooth structure, consider oral environmental conditions, accurately prepare cavities, and select and apply restorative materials are integral aspects. Recurrent caries around composites requires a triad of attention where the operator’s skills are cornerstones.

The effect of different liners on the bond strength of a compomer to primary teeth dentine: in vitro study

OBJECTIVE

This in vitro investigation should identify the effect of protective liners on dentine bond strength of a polyacid modified resin composite to dentine of primary teeth.

METHODS

Forty-two extracted caries-free primary molars were randomly assigned to seven groups (n = 6) and flattened. Six test groups were centrally covered with different protective liners/base materials: Kerr Life (KL), IRM zinc oxide eugenol cement (IRM), Ketac Bond (KB), Vitrebond (VB), Dycal (DY), and mineral trioxide aggregate (MTA). Specimens were bonded with Prime&Bond NT (PB) and restored with Dyract eXtra. The control group (C) did not receive liner pretreatment. After 24-h storage in Aqua dest. (37 °C), specimens were cut and regional microtensile bond strengths of the uncovered areas were tested. Fractography was conducted under a light microscope and further interface/surface analyses were performed under a SEM. Statistical appraisal was carried out using oneway ANOVA (mod. LSD test; p < 0.05).

RESULTS

Independent of the distance to the applied liner, all groups exhibited inferior μ-TBS to dentine of primary teeth compared to the control group (p < 0.05). The results were as follows in MPa(SD) ^x:significance level/percentage of adhesive fractures: PB: 34 (10)^A/72%; KL: 23 (25)^B/64%; KB: 15 (12)^C/76%; DY 15 (13)^C/55%; IRM: 14 (10)^C/68%; VB: 12 (10)^C/61%; MTA 12 (10)^C/69%.

CONCLUSIONS

Protective liners significantly reduced μ-TBS to dentine of primary teeth.

Characterization of Lactobacilli isolated from carious dentin after selective caries removal and cavity sealing

OBJECTIVE

To characterize lactobacilli isolated from residual carious dentin after selective caries removal (SCR), by observing the changes detected in their prevalence, diversity, and cariogenic potential after starvation stress caused by cavity sealing (CS).

DESIGN

Lactobacilli were cultured from carious dentin lesions (n = 16 patients) treated in a clinical trial, three months before and after CS. Presumptive lactobacilli were selected, isolated, and analyzed by Gram staining. Housekeeping gene sequences were used to identify the species (groEL, rpoA, pheS, and 16S rRNA).

RESULTS

N = 86 Lactobacillus spp. (n = 41 before and n = 45 after sealing) were genotyped by AP-PCR and analyzed for their cariogenic potential (acid production and acid tolerance). The proportion of lactobacilli to the total anaerobic counts was high, and a significant decrease was observed after sealing (median before sealing = 78.9; 25th-75th = 60.25-97.35; median after sealing = 0.00; 25th-75th = 0.00-77.08; p = 0.001). L. paracasei was the most prevalent species of lactobacilli in carious dentin (p = 0.02). L. rhamnosus prevalence increased to a proportion similar to L. paracasei after CS (p = 0.001). A total of 28 and 14 different genotypes were found before and after CS, respectively. There was no difference between the L. paracasei and the L. rhamnosus isolated from carious dentin, neither regarding acid production nor acid tolerance.

CONCLUSIONS

Although there was a significant reduction in lactobacilli in the residual carious dentin after SCR, some strains were capable of surviving after three months of CS. However, the sealed available nutrients are low and not sufficient for caries progression. Also, we believe that a longer follow up period may eliminate all the residual lactobacilli. L. paracasei prevailed in carious dentin in a proportion similar to L. rhamnosus in the sealed dentin. Characterization of lactobacilli after SCR and sealing may help the understanding the importance of genotyping of lactobacilli in carious microbiota.

Performance of Adhesives and Restorative Materials After Selective Removal of Carious Lesions: Restorative Materials with Anticaries Properties

Selective carious tissue-removal strategies require specific considerations in selection of restorative materials. A tight marginal seal placed over hard dentin and sound enamel is essential. For selective removal of carious tissue with permanent restoration, bioactive materials, such as high-viscosity glass-ionomer cement (HV-GIC) or calcium silicates, may be preferred over caries-affected firm or leathery dentin to improve remineralization. HV-GICs have the best clinical evidence of caries-arresting effect and demonstrate sufficient longevity as long-term provisional restorations that can later be used in open or closed sandwich restorations. As with any material, oral health maintenance remains important for long-term survival of restorations.

Systemic administration of probiotics reduces the severity of apical periodontitis

AIM

To evaluate the effect of systemic administration of probiotics on the severity of apical periodontitis (AP).

METHODOLOGY

Twenty-four male Wistar rats were used. AP was induced in the maxillary left/right first molars. The animals were arranged into groups: Control, Lactobacillus rhamnosus, and Lactobacillus acidophilus. Probiotics were administered orally for gavage (10⁹ colony-forming units diluted in 5 mL of water for 30 days) during the development of AP. After 30 days, cardiac puncture was performed to analyse the complete blood count. Moreover, microbiological analysis of the root canal contents and saliva was performed. Then, the animals were euthanized and the jaw removed for histopathological and IL-10, IL-1β and IL-6 immunolabeling analyses. After the Shapiro-Wilk test of normality, the Kruskal-Wallis followed by Dunn's test was performed for nonparametric data, and analysis of variance followed by the Tukey test was performed for parametric data (P < 0.05).

RESULTS

No significance difference was observed in the blood profiles and in the counts of microorganisms from the saliva samples among the groups (P > 0.05). Total microorganism counts in the root canal, the inflammatory infiltrate and the immunostaining for IL-1β and IL-6 in AP were significantly lower in the probiotic groups when compared with the control group (P < 0.05). IL-10 was significantly more immunolabled in the probiotic groups than in the control group (P < 0.05).

CONCLUSION

Supplementation with probiotics (Lactobacillus rhamnosus and Lactobacillus acidophilus) had a significant effect on the severity of apical periodontitis in rats, demonstrating the anti-inflammatory effect of probiotics on the development of apical periodontitis.

Novel metformin-containing resin promotes odontogenic differentiation and mineral synthesis of dental pulp stem cells

This represents the first report on the development of metformin-containing dental resins. The objectives were to use the resin as a carrier to deliver metformin locally to stimulate dental cells for dental tissue regeneration and to investigate the effects on odontogenic differentiation of dental pulp stem cells (DPSCs) and mineral synthesis. Metformin was incorporated into a resin at 20% by mass as a model system. DPSC proliferation attaching on resins was evaluated. Dentin sialophosphoprotein (DSPP), dentin matrix phosphoprotein 1 (DMP-1), alkaline phosphatase (ALP), and runt-related transcription factor 2 (Runx2) genes expressions were measured. ALP activity and alizarin red staining (ARS) of mineral synthesis by the DPSCs on resins were determined. DPSCs on metformin-containing resin proliferated well (mean ± SD; n = 6), and the number of cells increased by 4-fold from 1 to 14 days (p > 0.1). DSPP, ALP, and DMP-1 gene expressions of DPSCs on metformin resin were much higher than DPSCs on control resin without metformin (p < 0.05). ALP activity of metformin group was 70% higher than that without metformin at 14 days (p < 0.05). Mineral synthesis by DPSCs on metformin-containing resin at 21 days was 9-fold that without metformin (p < 0.05). A novel metformin-containing resin was developed, achieving substantial enhancement of odontoblastic differentiation of DPSCs and greater mineral synthesis. The metformin resin is promising for deep cavities and perforated cavities to stimulate DPSCs for tertiary dentin formation, for tooth root coatings with metformin release for periodontal regeneration, and for root canal fillings with apical lesions to stimulate bone regeneration.

Incorporation of chlorhexidine and nano-sized sodium trimetaphosphate into a glass-ionomer cement: Effect on mechanical and microbiological properties and inhibition of enamel demineralization

OBJECTIVE

To evaluate the antimicrobial/antibiofilm and mechanical properties, and the effect on enamel demineralization of a resin-modified GIC (RMGIC) containing CHX and nano-sized sodium trimetaphosphate (TMP).

METHODS

RMGIC was associated with CHX (1.25 or 2.5%) and/or TMP (7 or 14%). Antimicrobial and antibiofilm activity were assessed using agar diffusion test and evaluation of biofilm metabolism, respectively. In addition, fluoride (F) and TMP releases as well as the diametral tensile (DTS) and compressive (CS) strength were determined. The percentage of mineral loss (%SH), integrated loss of subsurface hardness (ΔKHN) and enamel F concentrations were also evaluated.

RESULTS

RMGICs containing CHX associated or not with TMP presented higher inhibition zones and effect on S. mutans biofilm. A reduction on CS was observed only for RMGIC + 2.5%CHX and on DTS for RMGIC + 2.5%CHX + 14%TMP. The highest F and TMP releases and lowest %SH and ΔKHN values were detected for RMGIC + 1.25%CHX + 14%TMP and RMGIC + 2.5%CHX + 14%TMP. Higher enamel F concentrations were observed for TMP groups.

CONCLUSION

1.25%CHX and 14%TMP increased antimicrobial/antibiofilm action and the ability to prevent enamel demineralization, with minimal effect on the mechanical properties of RMGIC.

CLINICAL SIGNIFICANCE

RMGIC containing CHX and TMP is an alternative material for patients at high risk for dental caries and can be indicated for low-stress regions or provisional restorations.

Ion release, antimicrobial and physio-mechanical properties of glass ionomer cement containing micro or nanosized hexametaphosphate, and their effect on enamel demineralization

OBJECTIVES

To evaluate the effects of hexametaphosphate microparticles (mHMP) or nanoparticles (nHMP) incorporated in glass ionomer cement (GIC) on antimicrobial and physico-mechanical properties, fluoride (F) release, and enamel demineralization.

MATERIAL AND METHODS

HMP solutions were obtained at concentrations of 1, 3, 6, 9, and 12%, for screening of antimicrobial activity. Next, mHMP or nHMP at 6, 9, and 12% were incorporated into a resin-modified GIC and the antibacterial activity was evaluated. The resistance to diametral tensile and compressive strength, surface hardness, and degree of monomer conversion as well as F and HMP releases of GICs were determined. Furthermore, specimens were attached to enamel blocks and submitted to pH-cycling, and mineral loss was determined. Parametric and non-parametric tests were performed, after checking data homoscedasticity (p < 0.05).

RESULTS

HMP solutions at 6, 9, and 12% demonstrated the best antibacterial activity. GIC containing HMP showed better antibacterial effects at 9 and 12% for nHMP. Regarding F and HMP releases, the highest levels of release occurred for groups containing 9 and 12% nHMP. With the increase in HMP concentration, there was lower mineral loss. However, the incorporation of mHMP or nHMP in GIC reduced values of physico-mechanical properties when compared to the control GIC.

CONCLUSIONS

nHMP improves antimicrobial activity and fluoride release, and decreases enamel demineralization, but reduces the physico-mechanical properties of GIC.

CLINICAL RELEVANCE

The association of GIC/HMP could be an alternative material for patients at high risk for dental caries and could be indicated for low-stress regions or provisional restorations.

Relative effectiveness of direct and indirect pulp capping in the primary dentition

INTRODUCTION

Carious or traumatised teeth with a normal pulp status or with reversible pulpitis need an indirect or direct pulp capping procedure to keep the pulp vital.

AIM

To evaluate the clinical outcome of both interventions for treating vital primary teeth.

STUDY DESIGN

Two reviewers on Pubmed and ISI Web of Science performed a comprehensive literature review of publications from 1966 until December 2017. Among PubMed abstracts, publications were selected according to the following criteria: prospective clinical study, correct indication for the performed treatment, and clear definition of clinical and/or radiographic success criteria. The strict selection criteria limited the amount of randomised controlled trials (RCT) or controlled clinical trials (CT); especially for "indirect pulp therapy", "direct pulp capping" and the number of RCTs was limited.

CONCLUSIONS

Based on a systematic review (20 controlled clinical studies or randomised controlled clinical studies), the following statements can be given: Due to the opportunity of tissue repair, indirect pulp treatment can be an acceptable procedure for reversible pulp inflammation. The use of adhesives for indirect pulp capping in a single-visit procedure after gentle caries removal can be recommended. Successful pulp capping is possible under defined conditions (symptom-free tooth, disinfection of pulp exposures, Class-I cavity) and appropriate sealing of the cavity with an effective dentine seal being a conditio sine qua non. There is maximum evidence for the use of disinfecting solutions prior to pulp capping and Dycal as pulp capping material. Longer follow-up periods, more clinical studies, comparable conditions, and clear definitions of evaluation criteria are needed to confirm the results of endodontic treatment in primary teeth.

Doxycycline-containing glass ionomer cement for arresting residual caries: an in vitro study and a pilot trial

In a previous study, we demonstrated that the incorporation of doxycycline hyclate (DOX) into resin-modified glass ionomer cement (RMGIC) inhibited important cariogenic microorganisms, without modifying its biological and mechanical characteristics. In this study, we keep focused on the effect of that experimental material as a potential therapy for arresting residual caries by analyzing other in vitro properties and conducting a pilot clinical trial assessing the in vivo effect of DOX-containing RMGIC on residual mutans streptococci after partial carious removal in primary molars. Specimens of the groups RMGIC (control); RMGIC + 1.5% DOX; RMGIC + 3% DOX; and RMGIC + 4.5% DOX were made to evaluate the effect of DOX incorporation on surface microhardness and fluoride release of RMGIC and against biofilm of Streptococcus mutans. Clinical intervention consisted of partial caries removal comparing RMGIC and RMGIC + 4.5% DOX as lining materials. After 3 months, clinical and microbiologic evaluations were performed. Data were submitted to ANOVA/Tukey or Wilcoxon/Mann-Whitney set as α=0.05. Fluoride release and surface microhardness was not influenced by the incorporation of DOX (p>0.05). There was a significant reduction of S. mutans biofilm over the material surface with the increase of DOX concentration. After clinical trial, the remaining dentin was hard and dry. Additionally, mutans streptococci were completely eliminated after 3 months of treatment with RMGIC + 4.5% DOX. The incorporation of DOX provided better antibiofilm effect, without jeopardizing fluoride release and surface microhardness of RMGIC. This combination also improved the in vivo shortterm microbiological effect of RMGIC after partial caries removal.

Bacterial reduction in sealed caries lesions is strain- and material-specific

Sealing can arrest caries lesions. We aimed to evaluate if sealing effects and kinetics are bacterial-strain and sealing-material specific. Human dentin discs were mounted in a dual-chamber device. Caries lesions were induced chemically and contaminated with either Lactobacillus rhamnosus (LR) or Streptococcus sobrinus (SS). For (1) kinetics assessment, the initial bacterial load and the sealing period were varied, and lesions sealed using a self-etch adhesive and composite. For (2) comparing materials, six sealing protocols (#1-#6) were evaluated: 1# Self-etch adhesive plus composite placed without a liner, or #2 calcium hydroxide, or #3 mineral trioxide aggregate, or #4 Biodentine liners; #5 antibacterial adhesive plus composite; #6 glass ionomer cement. Pulpal fluid flow was simulated during sealing. The outcome was the number of surviving bacteria (CFU) per g dentin. For LR, bacterial survival increased significantly with increasing initial bacterial load and decreased with longer sealing periods. The relative reduction followed a first-order kinetics. More LR survived under calcium hydroxide or MTA than other materials (p < 0.001). For SS, nearly no bacteria survived sealing regardless of sealing period, initial bacterial load or sealing material. In conclusion, sealing effects and kinetics were strain- and material-specific.

Effect of the addition of chlorhexidine and miswak extract on the clinical performance and antibacterial properties of conventional glass ionomer: an in vivo study

BACKGROUND

Antibacterial restorations can increase the success rate of minimum invasive dentistry especially in young permanent molars with deep carious lesions as an attempt to preserve maximum dental structure and avoid pulp exposure. Further research is warranted to evaluate different antibacterial agents.

OBJECTIVES

This study aimed to evaluate the efficacy of adding chlorhexidine gluconate (CHX) or aqueous miswak (Salvadora persica) extract on the clinical performance and in vivo antibacterial activity of conventional anhydrous glass ionomer cement (GIC).

DESIGN

The study was a randomized clinical trial. Sixty young permanent molars, with deep carious lesions in 6- to 9-year-old children were included. After randomization, atraumatic restorative treatment (ART) or stepwise excavation was performed followed by bacterial sampling from the center of the remaining carious dentine in the floor of the pulp. GIC powder was mixed with 0.5% chlorhexidine gluconate liquid in group I; with 100% aqueous miswak in group II; and with deionized water in group III (control). Clinical performance for all groups was assessed at 3, 6, and 9 months. After 9 months, restorations were removed and a second bacterial sample was collected for Streptococcus mutans (S. mutans) quantification and analysis by real-time polymerase chain reaction (PCR) test.

RESULTS

Results showed no statistically significant difference in the success rate of the three groups at the 3-month interval. At 6 and 9 months, however, restoration success was 75% then 60% in group I, 100% then 90% in group II, and 95% then 85% in control group. Group II and the control group showed statistically significant higher survival rates than group I. All groups showed reduction in S. mutans counts in underlying dentine, but the percent reduction was significantly higher in group I. (P < 0.001).

CONCLUSIONS

The addition of CHX and miswak to GIC showed superior antibacterial properties than conventional GIC, without seriously affecting the clinical performance of the restoration until the 6-month follow-up, but failure significantly increased in terms of marginal defects at 9 months with CHX (group 1).

The influence of the lining material on the repair of the infected dentin in young permanent molars after restoration: A randomized clinical trial

Aim:

This study evaluated the impact of liner material on the fluorescence, morphological and mineral characteristics of permanent carious dentin after cavity sealing.

Methods:

Thirty children (11.0 ± 2.7 years old) presenting at least one active deep carious lesion in permanent molars were selected. Fragments of carious dentin were removed from teeth before lining the cavity (baseline samples) with high-viscosity glass ionomer cement (G1) or an inert material (wax - G2). Cavities were restored with composite resin and reopened 60 days later, and other fragments were removed (60-day sample). The laser fluorescence (LF) readings and morphological and mineral changes of both groups were compared.

Results:

After 60 days, forty teeth were available for evaluation. Lower LF means were obtained (Wilcoxon signed-rank test; P < 0.05), and enhanced calcium and phosphorus levels were detected for both groups (t-test, P < 0.05). An uptake of fluorine was observed only in G1 (t-test; P < 0.05). Regardless of the group, baseline samples exhibited clear signs of bacterial invasion, and the collagen fibers were exposed; the 60-day samples showed a better-organized tissue with a more compact intertubular dentin.

Conclusion:

Caries arrestment with dentin reorganization occurs regardless of the lining material placed in contact with the infected dentin.

Clinical Performance of Composite Restorations with Resin-modified Glass Ionomer Lining in Root Surface Carious Lesions

Objective: The purpose of this study was to evaluate the clinical performance of composite restorations in root surface carious lesions with or without resin-modified glass ionomer lining.

Methods and Materials: The sample consisted of 25 female and 14 male patients. A maximum of four lesions were included for each patient. After caries removal, the depth, length, and width of the cavity were measured. Lesions in the same patient were randomly divided into two groups, and the dentin surfaces were either lined with resin-modified glass ionomer liner (Glass Liner II) or left as they were. Self-etch adhesive (All Bond SE) was applied and cured for 20 seconds. All cavities were restored with nanohybrid anterior composite resin (Clearfil Majesty Esthetic). Two experienced clinicians evaluated the marginal adaptation (retention) rate, anatomic form, secondary caries, sensitivity, and marginal staining of restorations at the end of the first week and at six, 12, and 18 months posttreatment. The data were statistically analyzed using the Chi-square and two-way repeated measures tests.

Results: At the end of 18 months, a total of five lined and three unlined restorations were lost. There was no significant relationship between marginal adaptation and cavity lining at six, 12, and 18 months (p&gt;0.05). Although marginal stainings of restorations were mostly localized, the total number of localized or generalized discolored restorations increased with time (p&lt;0.001). There was a statistically significant relationship between marginal staining and smoking (p&gt;0.05). There was no significant relationship between marginal staining and frequency of toothbrushing at six, 12, and 18 months (p=0.286, p=0.098, and p=0.408, respectively).

Conclusion: Within the limitations of this study, both restorative applications were accepted as clinically appropriate.

Clinical, mineral and ultrastructural changes in carious dentin of primary molars after restoration

INTRODUCTION

Partial caries removal has been shown to be an effective method to treat deep carious lesions in deciduous teeth. Nevertheless, the possibility of keeping infected dentin in the cavity still requires additional investigation. The objective of this research was to describe changes in primary infected dentin after restoration with glass ionomer cement.

METHODS

Dentin from 45 primary molars with deep and active carious lesions was evaluated using clinical and laboratory criteria, before and 60 days after restoration. The clinical analysis evaluated dentin colour (CO), dentin consistency (COS) and laser fluorescence (LF). The laboratory procedures assessed bacterial contamination and mineral content (MC), and evaluated the dentin ultrastructure and collagen content. Data on CO, COS, LF and colony forming units were analysed using the Wilcoxon signed-rank test; MC, bacterial counts and collagen evaluations were evaluated using the Student's t-test.

RESULTS

After 60 days, lower values of LF were observed, together with a lower bacterial count, and a higher COS was found, with an increase in calcium, phosphorus and collagen contents. Differences were not detected for CO or for fluorine content. Baseline samples showed enlarged tubules with bacterial invasion; 60-day samples showed better organised tissue, with a more compact intertubular dentin and narrower tubules.

CONCLUSION

It is concluded that appropriate cavity sealing can promote beneficial changes in deep carious lesions of primary teeth, even in the presence of infected dentin.

Antimicrobial activity of alexidine, chlorhexidine and cetrimide against Streptococcus mutans biofilm

Background

The use of antimicrobial solutions has been recommended to disinfect demineralized dentin prior to placing the filling material. The aim of this study was to evaluate the ability of several antimicrobials in controlling Streptococcus mutans (SM) biofilm formed in dentin.

Methods

Antimicrobial activity of 0.2% and 2% chlorhexidine (CHX), 0.2% cetrimide (CTR) and 0.2%, 0.5%, 1% and 2% alexidine (ALX) was assayed on 1-week SM biofilm formed on standardized coronal dentin blocks. Results of SM biofilm antimicrobial activity by different protocols were expressed as the kill percentage of biofilm and the term “eradication” was used to denote the kill of 100% of the bacterial population. To compare the efficacies of the different protocols the Student t test was used, previously subjecting data to the Anscombe transformation.

Results

All ALX concentrations tested and 0.2% CTR achieved a kill percentage higher than 99%, followed by 2% CHX with percentages above 96% (no statistically significant difference among them). Whereas 2% ALX and 0.2% CTR respectively showed eradication in 10 and 9 of the twelve specimens, 0.2% CHX did not produce eradication in any case.

Conclusions

The present study shows that, when used for one minute, 2% and 1% alexidine, and 0.2% cetrimide, achieve eradication of Streptococcus mutans biofilm in most specimens when applied to a dentin-volumetric model.

Genotypic diversity and virulence traits of Streptococcus mutans isolated from carious dentin after partial caries removal and sealing

The aim of this study was to compare the genotypic diversity and virulence traits of Streptococcus mutans isolated from carious dentin before and after partial dentin caries removal (PDR) and sealing. Carious dentin samples were obtained three months before and after the PDR and cavity sealing. Up to seven isolates of each morphological type of S. mutans were selected and strain identity was confirmed using gtfB primer. Genotyping was performed by arbitrary primer-PCR (AP-PCR). Acidogenesis and acidurance of the genotypes were evaluated as virulence traits. A paired t-test and a Wilcoxon test were used to compare the virulence of genotypes. A total of 48 representative S. mutans isolates were genotyped (31 before and 17 after the sealing). At least one of the genotypes found before the sealing was also found on dentin after the sealing. The number of genotypes found before the sealing ranged from 2 to 3 and after the sealing from 1 to 2 genotypes. No difference was observed in the acidogenesis and acidurance between genotypes isolated before and after the sealing. In conclusion, genotypic diversity of S. mutans decreased after the PDR and sealing, but the virulence traits of S. mutans remained unchangeable.

Two-year clinical study on postoperative pulpal complications arising from the absence of a glass-ionomer lining in deep occlusal resin-composite restorations

AIM

To observe the effects of glass-ionomer cement (GIC) lining on the risk of pulpal complications in deep occlusal cavities with resin-based restorations.

METHODS

Fifty-three patients, aged 18-30 years, who had one or two deep occlusal carious lesions (≥3 mm in depth) in molars, were recruited. Dental caries were removed, and the prepared cavity was restored with resin composite using one of two restorative procedures: (a) without GIC lining; and (b) with (resin-modified) GIC lining. Restored teeth were evaluated for any pulpal complications (subjective symptoms, objective signs or loss of tooth vitality) at 1 month (baseline), 1 year, and 2 years after restoration.

RESULTS

After excluding shallow cavities, 31 restorations without GIC lining, and 31 restorations with GIC lining, were placed and recalled at baseline without any pulpal complications. At the 1- and 2-year recalls, six patients who had restorations in group 1, and 13 in group 2, had dropped out. None of the remaining teeth in the two groups exhibited pulpal complications at either recall period, regardless of GIC lining placement.

CONCLUSIONS

The absence of GIC lining does not increase the risk of pulpal complications in deep occlusal cavities restored with resin-based restorations in either the short or long term.

Mechanical and biological characterization of resin-modified glass-ionomer cement containing doxycycline hyclate

OBJECTIVES

To characterize the mechanical and biological properties of a resin-modified glass ionomer cement (RMGIC) containing doxycycline hyclate.

METHODS

The antibacterial effect of RMGIC containing 1.5, 3.0 and 4.5% doxycycline hyclate was assessed using two experiments - agar diffusion test for 24h and biofilm assay for 24h and 7 days - against some cariogenic bacteria. Briefly, base layers of BHI agar and 300μL of each inoculum were prepared in Petri dishes with 6 wells that were completely filled with materials. After 24h incubation, zones of bacterial growth inhibition were measured using a digital caliper. Biofilm assays were conducted using RMGIC specimens immersed in 24-well plates containing the inoculum in BHI broth. After 24h and 7 days, each specimen were removed, vortexed and the suspension diluted and inoculated in BHI plates for subsequent bacterial counting. Cytotoxicity tests used 50 specimens made in sterilized metal molds, including Vitrebond as positive control. Extracts from every specimen were applied on the MDPC-23 odontoblast-like cells for 24h. The MTT assay and SEM evaluation determined cell metabolism and morphology, respectively. 80 cylindrical specimens were made from the previously cited groups, and were submitted to testing with a universal testing machine (Instron 4411) using a crosshead speed of 1.0mm/min for compressive strength and 0.5mm/min for diametral tensile strength, respectively. Data from antibacterial and cytotoxic effects, and mechanical properties were submitted to appropriated statistical tests.

RESULTS

All tested groups showed growth inhibition of all tested strains (p<0.05) in 24h for both microbiological tests, but only 4.5% doxycycline have antibacterial effect after 7 days. None of doxycycline concentrations caused toxic effect to the MDPC-23 cells or presenting alterations to mechanical properties.

CONCLUSION

The incorporation of up to 4.5% doxycycline hyclate into RMGIC inhibits important oral microorganisms, without modifying biological and mechanical characteristics of the dental material, suggesting a new alternative for the treatment of dental caries.