Development Of Secondary Caries Research Articles

Evaluation of the Protective Effect of Silver Diamine Fluoride Against Secondary Caries Development in Composite Resin Restorations Comparatively with Sodium Fluoride and Titanium Tetrafluoride by Micro Computed Tomography

Objective: The aim of this study is to evaluate the effectiveness of 38% silver diamine fluoride (SDF) in preventing secondary caries formation by comparing it with other fluoride-containing remineralization agents such as sodium fluoride and titanium tetrafluoride in vitro. Material and Methods: Cavities of 4x2x2 mm were prepared on the mesial, distal, buccal and lingual surfaces of the extracted 12 intact human third molars. 38% silver diamine fluoride solution was applied to the first group, 2% NaF solution to the 2nd group, 2% TiF4 solution to the 3rd group and deionized water to the 4th group. After the solutions were applied, the cavities were restored with composite resin. Then, all samples were aged by thermal cycle method and sterilized by autoclave. The volume of the lesions formed by keeping the samples in 5% sucrose solution containing Streptococcus mutans and Lactobacillus acidophilus for 28 days was evaluated by micro computed tomography method. Data analysis of the study was performed using SPSS 21.0 V (IBM, Chicago, USA) statistical package program. Group results were compared using one-way analysis of variance (ANOVA) test (p>0.05). Results: Although the secondary caries lesion volume was found to be lower in the silver diamine fluoride applied group compared to the other groups, there was no statistically significant difference between the groups. Conclusion: These results show that the effectiveness of silver diamine fluoride to prevent secondary caries formation in composite resin restorations should be investigated with longer-term studies.

Matrix metalloproteinase inhibitors in restorative dentistry.

Matrix metalloproteinases (MMPs) have been identified as agents that disintegrate the collagen structures of dental hybrid layers, resulting in reduced restorative bond strength. Multiple MMP inhibitors (MMPIs) are known to counteract this degenerative mechanism, thereby preserving bond strength and promoting the longevity of resin-based restorations. Additionally, literature suggests that certain MMPI materials possess antimicrobial/anticariogenic properties, potentially reducing the risk of secondary caries development. Therefore, this review article aims to narrate on the integration of matrix metalloproteinase inhibitors into adhesive systems and their impact on bond strength.

Assessment of Interleukin-6 Levels and Lactobacillus casei Counts in Pediatric Stainless Steel and Zirconia Crowns: A Comparative Study.

Pediatric dental crowns play an integral role as they maintain the form and function and prolong the life of the affected tooth. However, placing a crown in the oral cavity creates a new niche for the adhesion of microorganisms that can lead to plaque accumulation, gingival inflammation, and the development of secondary caries, which in the long term might determine the clinical success of the restored tooth. The present study allowed us to assess the changes caused by the full coverage restorations at a clinical, immunological, and microbiological level using enzyme-linked immunosorbent assay (ELISA) and microbial analysis. The in vivo analysis consisted of a total of 26 children aged 3-10 years. They were divided into two groups, group I (n = 13) children receiving preformed zirconia crowns and group II receiving stainless steel crowns (SSCs). Plaque index (PI) scores, gingival index (GI) scores, and interleukin-6 (IL-6) levels were assessed at baseline and at 45 days of follow-up. The in vitro part of the study consisted of 13 preformed zirconia crowns and 13 SSCs which were immersed in artificial saliva containing strains of Lactobacillus casei which were then processed for their microbial analysis. On mean comparison, preformed zirconia crowns performed superiorly both clinically and immunologically compared to SSCs. Microbial analysis using independent t-test revealed that the colony-forming units (CFU) per milliliter was statistically significantly higher for the SSCs, and the mean difference among the groups was statistically significant (p < 0.01). Preformed zirconia crowns can be a relative replacement for SSCs in primary teeth with the advantage of esthetics and superior periodontal health. Saharia NP, Malik M, Jhingan P, et al. Assessment of Interleukin-6 Levels and Lactobacillus casei Counts in Pediatric Stainless Steel and Zirconia Crowns: A Comparative Study. Int J Clin Pediatr Dent 2024;17(4):395-403.

The formation of cariogenic plaque to contemporary adhesive restorative materials: an in vitro study

The research exploiting the ability of dental materials to induce or prevent secondary caries (SC) development still seems inconclusive. Controlling bacterial adhesion by releasing bacteriostatic ions and improving the surface structure has been suggested to reduce the occurrence of SC. This paper analyses the impact of five distinctively composed dental materials on cariogenic biofilm formation. Forty-five specimens of three composites (CeramX Spectra ST, Admira Fusion, Beautifil II) and two glass–ionomers (Fuji II LC, Caredyne Restore), respectively, were incubated in bacterial suspension composed of Streptococcus mutans, Lactobacillus acidophilus, Streptococcus mitis, Streptococcus sanguinis, and Streptococcus salivarius at pH 7.0 and 5.5. Coverslips were used as a control. Adhered bacteria were collected after 2, 4, 6, 12, 24, and 48 h and analyzed using quantitative polymerase chain reaction (qPCR). Fluoride leakage was measured at each collection. The specimens’ surface topography was assessed using interferometry. In the present study, surface roughness seemed to have a partial role in bacterial adhesion and biofilm formation, together with chemical composition of the materials tested. Despite differences in fluoride leakage, biofilm accumulation was similar across materials, but the number of adhered bacteria differed significantly. A release of other ions may also affect adhesion. These variations suggest that certain materials may be more prone to initiating secondary caries.

Effect of a novel pH-responsive tertiary amine monomer dodecylmethylaminoethyl methacrylate modified resin adhesive on biofilm formation of Streptococcus mutans and Lactobacillus casei in vitro

Objective: To explore the application prospect of a new pH-responsive tertiary amine monomer dodecylmethylaminoethyl methacrylate (DMAEM) modified resin adhesive (DMAEM@RA) in the prevention and treatment of secondary caries. Methods: Five percents DMAEM was added to the resin adhesive to synthesize DMAEM@RA for modifying. Streptococcus mutans (Sm) and Lactobacillus casei (Lc) biofilms were cultured on resin adhesive and DMAEM@RA, respectively. The culture systems were set up at pH=7.4, 6.0, 5.5, and 5.0. The antimicrobial activity of DMAEM@RA was evaluated by quantitative PCR. The effects of DMAEM@RA on biofilm thickness, bacterial amount, and extracellular polysaccharides were studied by scanning electron microscope (SEM) and extracellular polysaccharide staining. Real-time fluorescence quantitative PCR was used to study the effect of DMAEM@RA on the expression levels of cariogenic genes in Sm. Results: DMAEM@RA could significantly reduce the amount of Sm and Lc under acidic conditions, especially Lc. At pH=5.0, the logarithm value of co-cultured Sm bacteria [lg (CFU/ml)] in DMAEM@RA group (7.58±0.01) was significantly lower than that in control group (7.87±0.03) (t=14.32, P<0.001), and the logarithm value of Lc bacteria [lg (CFU/ml)] (7.29±0.04) was also significantly lower than that in control group (7.93±0.15) (t=6.93, P=0.002). SEM observed that the bacteria decreased and the cell fragments appeared in DMAEM@RA group. In addition, DMAEM@RA significantly reduced the biomass of extracellular polysaccharides in the dual-species biofilm under acidic conditions. At pH=5.0, the biomass of extracellular polysaccharides in DMAEM@RA group [(25.13±3.14) mm3/mm2] was significantly lower than that in the control group [(42.66±7.46) mm3/mm2] (t=3.75, P=0.020). DMAEM@RA could significantly up-regulate the expressions of gtfB and gtfC genes in Sm under acidic conditions. At pH=5.0, gtfB and gtfC genes were significantly up-regulated by (14.64± 0.44) times and (2.99±0.20) times, respectively (t=-42.74, P<0.001; t=-13.55, P<0.001). Conclusions: The DMAEM@RA has a good antibacterial effect under acidic conditions, demonstrating that it has a good potential to prevent the occurrence and development of secondary caries.

A low-shrinkage-stress and anti-bacterial adherent dental resin composite: physicochemical properties and biocompatibility.

Polymerisation shrinkage and biofilm accumulation are the two main problems associated with dental resin composites (DRCs) that induce secondary caries, which can cause restoration failure. Polymerisation shrinkage can lead to microleakage gaps between the tooth and the DRCs, causing the aggregation of bacteria and development of secondary caries. Reducing the shrinkage stress (SS) and improving the resistance to bacterial adhesion have always been the focus of this field in modifying DRCs. A thiol-ene resin system can effectively reduce the polymerisation SS via its step-growth mechanism for delaying the gel point. Fluorinated compounds can reduce the surface free energies, thereby reducing bacterial adhesion. Thus, in this study, a range of mass fractions (0, 10, 20, 30, and 40 wt%) of a fluorinated thiol-ene resin system were added to a fluorinated dimethacrylate resin system/tricyclo decanedimethanol diacrylate to create a fluorinated methacrylate-thiol-ene ternary resin matrix. DRCs were prepared using the obtained ternary resin matrix, and their physical and chemical properties, effect on bacterial adhesion, and biocompatibility were investigated. The results demonstrated that the volumetric shrinkage and SS of the DRCs were reduced with no reduction in conversion degree even after the thiol-ene resin system was added. All DRC-based fluorinated resin systems exhibited an excellent anti-bacterial adhesion effect, as evidenced by the colony-forming unit counts, live/dead bacterial staining, and crystal violet staining tests against Streptococcus mutans (S. mutans). The genetic expressions associated with the bacterial adhesion of S. mutans were substantially affected after being cultured with fluorinated DRCs. All fluorinated DRCs demonstrated good biocompatibility through the in vitro cytotoxicity test and live/dead staining images of the L-929 cells. The above results illustrate that the DRCs based on the fluorinated methacrylate-thiol-ene resin matrix can be potentially applied in clinical practice due to their low SS and anti-bacterial adhesion effect.

Improving the Antibacterial Properties of Dental Bonding Materials Loaded with Silver Compounds.

Biofilm accumulation, the appearance of white spot lesions and the development of secondary caries are the main complications in orthodontic patients. A promising approach to fight this situation is the development of adhesive cements with improved antibacterial properties. The aim of the present study was to evaluate the possibility of improving the antibacterial properties of glass ionomer cements by incorporating different types of antimicrobial compounds without altering their physical and mechanical properties. Different concentrations of silver carbonate (SC) and an inorganic glass with encapsulated silver were added to the glass ionomer cement, as well as chitosan, to achieve synergistic antibacterial activity. Variations in the antibacterial capacity were evaluated using the agar diffusion test; the potential alteration of the physical and mechanical properties of the material was analyzed by the shear bond strength test. SEM characterization and colorimetric evaluation were also conducted. Samples of SC up to 1% and inorganic glass with encapsulated silver up to 5% showed significant improvement in their antibacterial ability without compromising shear strength. The highest antimicrobial activity was observed for Lactobacillus acidophilus, with inhibition zones of 3.8 and 3.1 mm for SC and inorganic glass, respectively. The characterization of the samples did not detect any major structural changes between the different samples. The only group that underwent a noticeable color change was the group with SC. The results show that the incorporation of silver carbonate and inorganic glass with encapsulated silver provided the glass ionomer cement with an antibacterial capacity without compromising the bond strength and without modifying the structure of the material.

Laboratory assessment of the accuracy of the fit of artificial crowns to tooth stumps

Relevance. Among the variety of reasons for unsatisfactory results of treatment of patients with artificial crowns and their premature removal or cementation, the researchers highlight the development of secondary caries. One of the significant reasons for its occurrence is the quality of the marginal fit of artificial crowns.&#x0D; The goal is to perform a laboratory assessment of the thickness of the cement film in the area of ​ ​ the edge of the artificial crown and establish the degree of its influence on the probability of the development of the carious process.&#x0D; Procedure. Splints of 50 freshly removed teeth covered with artificial crowns were made, on which the thickness of the cement film was measured, and the presence of caries at the edge of the artificial crown was determined.&#x0D; Results. The development of caries under the artificial crown is typical of teeth dissected with a ledge. The threshold value of the thickness of the cement film, above which caries more often developed in the studied sample of teeth, was 115-120 microns. The probability of unacceptable thickness of the cement film and the development of caries in teeth prepared with a shoulder is 6.6 times higher than in preparation without a shoulder.

The strength of restorations of hard tooth tissues with changes in atmospheric pressure, &lt;i&gt;in vitro&lt;/i&gt; studies

BACKGROUND: It is known that the development of the carious process is promoted by microorganisms that secrete waste products that penetrate into the tooth tissue during the depressurization of the filling material. That is why high-quality restoration prevents the development of secondary caries.&#x0D; AIM: Based on the study of the edge fit of restorations made of various types of filling materials, when restoring the chewing surface of the tooth, to determine the most optimal method of filling, which reduces the likelihood of violation of the edge fit of the seal in cases of significant changes in atmospheric pressure.&#x0D; MATERIALS AND METHODS: The removed teeth were prepared and treated with the Single Bond Universal adhesive system, the samples were divided into 4 groups, the cavities were filled according to the classical method with traditional composite materials Estelite Sigma Quick (Tokuyama Dental), OptiShade (Kerr) and materials of the bulk fill Tetric N-Ceram (Ivoclar Vivadent), SonicFill (Kerr). After sealing, groups 3 and 4 were placed in a pressure chamber (the study was conducted at the Department of Aviation and Space Medicine) and exposed to low atmospheric pressure. Next, the restoration slots were made and the study was carried out using a scanning electron microscope JEOL JSM-6380LV.&#x0D; RESULTS: As a result of microscopic studies, a violation of the marginal fit along the filling-tooth border was determined in all samples sealed with traditional composite materials (Estelite Sigma Quick, OptiShade) 65 9.18% (p 0.05) and bulk fill group materials (Tetric N-Ceram, SonicFill) 98 2.69%, (p 0.05) in cases of exposure to low atmospheric pressure. In the samples that were not exposed to atmospheric pressure, the marginal depressurization was 12 6.25% (p 0.05) Estelite Sigma Quick, OptiShade and 21 7.84% (p 0.05) Tetric N-Ceram, SonicFill.&#x0D; CONCLUSION: It has been proved by laboratory method that traditional composite materials and bulk fill group materials are rational to use only in persons who are not associated with extreme effects on the body, since in cases of exposure to atmospheric pressure, there are violations of the marginal fit of the material along the sealtooth border.

Leaching components and initial biocompatibility of novel bioactive restorative materials.

Bioactive restorative materials were developed on the premise that direct restorations should not only serve the purpose of reconstructing dental hard tissue defects but also exhibit biological features that prevent secondary caries development, without having adverse effects on the host cells. This study focuses on assessing the in vitro biocompatibility of two novel bioactive restorative materials. Specimens of the bioactive restorative materials, Cention Forte (CF) and ACTIVA BioACTIVE RESTORATIVE (AB), a glass ionomer cement/glass hybrid (EQUIA Forte HT, EF) and an established nanohybrid composite (Venus Diamond, VD) were produced and finished. The specimens were eluted in water and methanol and the resulting eluates were analyzed via gas chromatography-mass spectrometry. hGF-1 cells were exposed to eluates prepared in cell culture medium. Cellular ATP levels, oxidized glutathione concentration, caspase-3/7 activity and the inflammatory response (IL-6 and PGE2 levels) were determined. Microscopic images were taken to examine the cell morphology. Methyl methacrylate and 2-Hydroxyethyl methacrylate were the main monomers detected in CF and AB eluates. All materials inhibited cell proliferation and led to significantly reduced ATP-levels. The cells exhibited a healthy morphology in the presence of CF and AB. Cells exposed to VD showed increased oxidized glutathione levels. Only EF led to enhanced caspase-3/7 activity. CF and AB caused IL-6 levels to increase, while EF and AB led to enhanced PGE2 levels. CF and AB are promising materials from a biological point of view and seem to have improved bioactive properties compared to glass ionomer cements.

Microleakage Among Different Dental Restorative Materials: Causes, Detection, and Impact on Marginal Integrity

Dental restorative materials are essential components in the field of dentistry, serving as compounds or substances used to address a wide spectrum of dental concerns, including cavities, tooth decay, fractures, and cosmetic enhancements. These materials, encompassing amalgam, composite resins, glass ionomer cement, and compomers, are carefully selected based on their specific properties and the requirements of the restorative procedure. However, dental restorations are intricate processes influenced by patient factors and material behaviour, which can lead to various complications. Among these, microleakage emerges as a prevalent and multifaceted issue, with causes ranging from polymerization shrinkage during material curing to thermal changes, cyclic loading, and moisture contamination. The consequences of microleakage are far-reaching, encompassing clinical challenges such as the development of secondary caries, tooth sensitivity, aesthetic concerns, and the potential for restoration failure. The susceptibility to microleakage varies among different dental restoration materials, with amalgam typically exhibiting lower susceptibility compared to more modern alternatives like composite resins and compomers. Glass ionomer cement, when employed with appropriate moisture control, can demonstrate improved resistance to microleakage over time. Detecting microleakage necessitates various methods, including radiography, dye penetration tests, electron microscopy, and microcomputed tomography. Effective prevention and management strategies involve the use of modern adhesive systems, precise restoration techniques, and patient education on maintaining optimal oral hygiene. Continual advancements in dental materials and techniques further contribute to the ongoing efforts to mitigate the challenges posed by microleakage in the ever-evolving landscape of modern dentistry, ultimately enhancing patient outcomes and ensuring the longevity and success of dental restorations while prioritizing overall oral health.

Dentin-desensitizing biomaterials

Dentin hypersensitivity (DH) associated with dentinal tubule exposure is one of the most common causes of toothache with a rapid onset and short duration. Medication, filling repair, laser irradiation, crown therapy, and desensitizing toothpaste are standard clinical treatment strategies, but unsatisfactory treatment modalities are marked by long-term administration, poor dentinal tubule closure, microleakage, and the development of secondary caries. To improve the treatment efficiency of DH, numerous organic or inorganic biomaterials have been developed to relieve toothache and reverse the instability of desensitization. Biomaterials are expected to participate in dental remineralization to achieve desensitization. This review discusses various biomaterials for DH therapy based on different desensitization mechanisms, including dentinal tubule closure and dental nerve blockade, and presents a perspective on the underlying future of dentin regeneration medicine for DH therapy.

L-arginine-containing mesoporous silica nanoparticles embedded in dental adhesive (Arg@MSN@DAdh) for targeting cariogenic bacteria

Dental caries is the major biofilm-mediated oral disease in the world. The main treatment to restore caries lesions consists of the use of adhesive resin composites due to their good properties. However, the progressive degradation of the adhesive in the medium term makes possible the proliferation of cariogenic bacteria allowing secondary caries to emerge. In this study, a dental adhesive incorporating a drug delivery system based on L-arginine-containing mesoporous silica nanoparticles (MSNs) was used to release this essential amino acid as a source of basicity to neutralize the harmful acidic conditions that mediate the development of dental secondary caries. The in vitro and bacterial culture experiments proved that L-arginine was released in a sustained way from MSNs and diffused out from the dental adhesive, effectively contributing to the reduction of the bacterial strains Streptococcus mutans and Lactobacillus casei. Furthermore, the mechanical and bonding properties of the dental adhesive did not change significantly after the incorporation of L-arginine-containing MSNs. These results are yielding glimmers of promise for the cost-effective prevention of secondary caries.Graphical

Microbiological models for accelerated development of secondary caries in vitro

ObjectivesThe current study aimed to compare the efficacy of two in vitro microbiological models based on open and closed systems designed to obtain secondary caries in an accelerated and reproducible way. MethodsA conventional resin-based composite (RBC - Majesty ES-2; Kuraray, Japan) and a resin-modified glass-ionomer cement (RMGIC – Ionolux; VOCO, Germany) were used to restore standardized class II cavities (n = 4/tooth, cervical margin in dentin) in 16 human molars. The ability to produce secondary caries with Streptococcus mutans biofilms was tested using either an open-cycle or closed-cycle bioreactor (n = 8 specimens/model). Specimens were scanned before and after the biofilm exposure using micro-CT (Skyscan 1176, 9 µm resolution, 80 kV, 300 mA). Image reconstruction was performed, and demineralization depths (µm) were evaluated at the restoration margins and a distance of 1.0 mm. ResultsDentin demineralization could be observed in all specimens, and enamel demineralization in 50% of the specimens. The open system bioreactor produced lesions with significantly higher overall demineralization depths (p < .001). However, demineralization depths at a 1.0 mm distance from the restoration margins showed no difference between open and closed systems or materials. In the open system, significantly lower demineralization depths were observed in proximity to RMGIC than RBC (p < .001), which was not significantly different in the closed system (p = .382). ConclusionsBoth systems produced in vitro secondary caries in an accelerated way. However, the open-cycle bioreactor system confirmed the caries-protective activity exerted by the RMGIC material in contrast to the RBC, better simulating materials’ clinical behavior. Clinical significanceThe possibility of obtaining accelerated and reproducible secondary caries development in vitro is fundamental in testing the behavior of conventional and yet-to-come restorative dental materials. Such systems can provide faster outcomes regarding the performance of dental restorative materials compared to clinical studies, notwithstanding the importance of the latter.

Glucosyltransferase-modulated Streptococcus mutans adhesion to different surfaces involved in biofilm formation by atomic force microscopy.

Biofilm on dental restorative materials is an important determinant in the etiology of secondary caries development. Formation of biofilm involves adhesion of bacteria onto substrate, bacterial cell, and biofilm surfaces. Glucosyltransferase B and C (GtfB and GtfC) are essential factors for regulation of Streptococcus mutans biofilm formation, but the mechanisms involving different kinds of bacterial adhesion still lack detailed description. In this study, nanoscale adhesion force measurement was performed using atomic force microscopy. Bacteria-coated cantilevers were used to probe S. mutans adhesion to substrates, bacterial cells, and early biofilms. Two representative dental materials, glass ionomer cement (GIC) and composite resin, served as substrates. It was found that deletion of gtfB and gtfC genes both reduced adhesion forces of S. mutans toward substrate and bacterial cell surfaces (P < 0.05). Notably, reduction of the gtfB gene remarkably decreased bacterial adhesion to biofilm surfaces (P < 0.05), while gtfC showed no obvious effect during this stage. Biofilms cultured on GIG further decreased cell-biofilm adhesion, compared with those on resin (P < 0.05). Confocal fluorescence images and scanning electron microscopy images showed that deletion of gtfB lead to reduced microcolony formation and less production of exopolysaccharides (EPSs) in the biofilm, and after bacterial culturing on GIC, the EPS content was further decreased. Our findings suggest that EPSs mainly mediate bacterial adhesion to early biofilm surface. Deletion of gtfB and coculture with GIC could significantly reduce the cell-biofilm adhesion, which is probably through decreasing of EPS production. gtfB exerts a critical role in the bacterial adhesion for the whole process of biofilm development, while gtfC possibly works only in the early stages.

Evaluation of the effectiveness of orthopedic treatment with fixed prostheses made using digital and traditional technologies

The aim of the study was to conduct a clinical assessment of the effectiveness of orthopedic treatment with fixed prostheses made using digital and traditional technologies. The clinical study involved 103 patients (52 men and 51 women) aged from 29 to 70 years. The patients were divided into two groups. The first group consists of 54 patients (28 men and 26 women) aged from 29 to 70 years, whose orthopedic treatment was carried out with non-removable metal-ceramic prostheses made using digital technologies. The second group consists of 49 patients (24 men and 25 women) aged 33 to 70 years, whose orthopedic treatment was carried out with non-removable metal-ceramic prostheses made using traditional technologies. The evaluation of the results of orthopedic treatment was carried out 1 year after the reinforcement of the prostheses with cement based on the criteria of the modified USPHS test for the clinical assessment of the condition of non-removable prostheses. The results obtained allow us to conclude that the technologies of intraoral laser scanning, computer modeling and automated production, in comparison with traditional technology, allow us to obtain fixed orthopedic structures with a shorter period of getting used to the prosthesis, better edge fit quality, preventing the development of secondary caries, and prevent the cementation of prostheses (p&lt;0,005).

The reciprocal interaction between fluoride release of glass ionomers and acid production of Streptococcus mutans biofilm

ABSTRACT Objectives The aim of this study was to demonstrate the mode of action of glass ionomers (G-Is) against cariogenic biofilms in the slow fluoride release phase by analyzing the reciprocal interaction between fluoride release from G-Is and acid production of Streptococcus mutans biofilm. Methods G-Is discs in the slow fluoride release phase were prepared and 51 h-old S. mutans biofilms were formed on these discs. The interrelationship between the acid production of the biofilm and the fluoride release of the G-Is discs was investigated by analyzing both factors simultaneously during the biofilm formation period. The composition of the 51 h-old biofilms was then examined using microbiological, biochemical, and confocal laser scanning microscopic methods. Results Acid production by the cariogenic biofilm, particularly at < pH 5, promotes G-Is fluoride release. Conversely, G-Is fluoride release inhibits the acid production of the cariogenic biofilm. This reciprocal interaction results in the reduction of virulence such as extracellular polysaccharides formation and cariogenic biofilm bio-mass, which may reduce the potential of secondary caries development around G-Is. Conclusions These results suggest that G-Is may play a role in preventing the development of secondary caries during the slow fluoride release phase.

The Relationship of Caries Risk and Oral Hygiene Level with Placement and Replacement of Dental Restorations.

To assess the caries risk and oral hygiene level that affect the placement and replacement of restorations. A practice-based study performed in private clinics. A total of 76 dentists participated. The sample consisted of 10,076 restorations of >14-year old patients collected by volunteer dentists over a period of two months. Clinicians were asked to record the details of their patients and also the state of oral hygiene and caries risk of each patient. The data were analysed using Microsoft Excel and SPSS 20.00 software. It was considered that a P value less than 0.05 was significant. 50.9% restorations replaced were due to secondary caries with moderate oral hygiene, with no significant differences. Of Class II type, 75% were replaced in moderate oral hygiene with a significant difference. There was a significant difference between the use of amalgam and composite according to the state of oral hygiene. 47.7% of the individuals who had their restorations replaced due to secondary caries had high caries risk. According to CI II cavity type, it was shown that 70.5% of the patients had moderate and 23% of the patients had high caries risk. Most restorations were replaced due to secondary caries. There is a synergetic relationship between oral hygiene level and caries risk in patients and the possibility of secondary caries development and restoration replacement.

The impact of glass ionomer cement and composite resin on microscale pH in cariogenic biofilms and demineralization of dental tissues

ObjectiveSecondary caries is among the most frequent reasons for the failure of dental restorations. Glass ionomer cement (GIC) restorations have been proposed to protect the surrounding dental tissues from demineralization through the release of fluoride and by buffering the acid attack from dental biofilms. In contrast, the lack of buffering by composite resin (CR) restorations has been suggested as a promoting factor for the development of secondary caries. MethodsThe present study employed transversal microradiography and confocal microscopy based pH ratiometry to quantify mineral loss and map microscale pH gradients inside Streptococcus mutans biofilms grown on compound specimens consisting of enamel, dentin and either GIC or CR. ResultsMineral loss in dentin was significantly lower next to GIC than next to CR, but no significant differences in local biofilm pH were observed between the two restorative materials. SignificanceThe cariostatic effect of GIC relies predominantly on the provision of fluoride and not on a direct buffering action. The lack of buffering by CR did not affect local biofilm pH and may therefore be of minor importance for secondary caries development.

The difference in radiopacity of microhybrid, nanofiller and nanohybrid composite resins with conventional periapical radiographic techniques

Objective: The radiopacity of dental composite restorative materials is important since it allows assessment of the integrity of composite restorations, accurate diagnosis of secondary caries development and evaluation of the interface between the com-posite restorative material and the tooth structure on the new materials introduced in the market nowadays. The purpose of this observation is to determine the differences of microhybrid, nanofiller and nanohybrid composite resins on their radiopacity using conventional periapical radiography techniques. Methods: Composite resins samples were divided into three groups; 30 samples each. Group I were microhybrid composite resin. Group II were nanofiller composite resin. Group III were nanohybrid composite resin. Each specimen was placed on a dental film and exposed using conventional radiographic techniques with the specification of 70 kVp, 8mA and 0.25s, then processed using instant film procedures. Observations were carried out using the densitometer. The results of calculations were analyzed by using the one way Anova test. Results: Significant radiopacity dif-ferences were occurred in those three groups (p&lt;0.05). Nanohybrid composite resin (2.32 mmAl) was significantly more ra-diopaque than microhybrid composite resin (2.20 mmAl) and nanofiller composite resin (2.10 mmAl). Conclusion: There are differences between microhybrid, nanofiller and nanohybrid composite resins. Resins that have the highest to the lowest ra-diopacity levels are nanohybrid, microhybrid, and nanofiller composite resin.