Comparison of human pulp response to total-etch and self-etch bonding agents

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>0.05). Although marginal stainings of restorations were mostly localized, the total number of localized or generalized discolored restorations increased with time (p<0.001). There was a statistically significant relationship between marginal staining and smoking (p>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.

Bacterial penetration of restored cavities using two self-etching bonding systems

Objective:

The aim of this study was to investigate the effects of two bonding systems, with and without antibacterial monomers, on marginal bacterial and dye leakage.

Materials and Methods:

Class V cavities were prepared in extracted teeth for a bacterial leakage test, and the teeth were sterilized using a steam autoclave. Four cavities were not restored for the controls, and the other teeth were divided into two groups (n = 16 cavities each): Clearfil Protect Bond group (CPB) and Clearfil SE Bond group (CSE). After application of the bonding agent, the cavities were restored using a composite resin (Clearfil AP-X). The teeth were thermocycled, stored in a broth culture of 1.56 × 108 colony forming units (CFU)/ml of Streptococcus mutans at 37°C for 10 days, and subsequently processed for bacterial staining. Sections from the demineralized teeth were evaluated under a light microscope. In the dye leakage test, the cavities were restored as described in the bacterial penetration test. After thermocycling, the teeth were immersed in 5% basic fuchsin for 24 h, and then divided in half and observed under a stereomicroscope. The data were analyzed using the Kruskal–Wallis and Mann–Whitney U-tests (P = 0.05).

Results:

The bacterial stain was detected at the cavity wall of five cavities in both bonding systems. Additionally, two cavities in the CSE group, one cavity in the CPB group, and all control cavities showed bacterial staining within the cut dentinal tubules. Dye staining at the axial cavity wall was detected in only three of the teeth for both bonding systems.

Conclusion:

The bonding systems used in this study provided an acceptable marginal seal to prevent bacterial and dye leakage.

Histological evaluation to study the effects of dental amalgam and composite restoration on human dental pulp: an in vivo study

OBJECTIVE

To study and compare the effects of dental amalgam and composite restorations on human dental pulp.

MATERIALS AND METHODS

One hundred sound premolars scheduled for orthodontic extraction were divided equally into two groups: group A, teeth restored with silver amalgam, and group B, teeth restored with composite resin. Each group was equally subdivided into two subgroups [extracted after 24 h (A-1 and B-1) or 7 days (A-2 and B-2)], and the histological changes in the pulp related to the two different materials at the two different intervals were studied.

RESULTS

It was found that after 24 h, the inflammatory response of the pulp in teeth restored with amalgam and composite was similar (p = 1.00). However, after 7 days, the severity of the inflammatory response of the pulp in teeth restored with amalgam was less compared to that in teeth restored with composite (p = 0.045).

CONCLUSION

This study confirmed that amalgam continues to be the mechanically as well as biologically more competent restorative material. Composite could be a promising restorative material to satisfy esthetic needs for a considerable period of time. However, its biological acceptance is still in doubt.

Effect of acid etching on marginal adaptation of mineral trioxide aggregate to apical dentin: microcomputed tomography and scanning electron microscopy analysis

The present investigation assessed the effect of acid etching on marginal adaptation of white- and gray-colored mineral trioxide aggregate (MTA) to apical dentin using microcomputed tomography (micro-CT) and scanning electron microscopy (SEM). Sixty-four extracted single-rooted human maxillary teeth were used. Following root-end resection and apical preparation, the teeth were equally divided into four groups according to the following root end filling materials: (i) white-colored MTA (WMTA), (ii) etched WMTA (EWMTA), (iii) gray-colored MTA (GMTA) and (iv) etched GMTA (EGMTA). After 48 h, the interface between root-end filling materials and the dentinal walls was assessed using micro-CT and SEM. Data were statistically analyzed using the Kruskal-Wallis and Dunn tests. Micro-CT analysis revealed gap volumes between the apical cavity dentin walls and EGMTA, GMTA, EWMTA and WMTA of (0.007 1±0.004) mm(3), (0.053±0.002) mm(3), (0.003 6±0.001) mm(3) and (0.005 9±0.002) mm(3) respectively. SEM analysis revealed gap sizes for EGMTA, WMTA, EWMTA and GMTA to be (492.3±13.8) µm, (594.5±17.12) µm, (543.1±15.33) µm and (910.7±26.2) µm respectively. A significant difference in gap size between root end preparations filled with GMTA and EGMTA was found (P<0.05). No significance difference in gap size between WMTA and EWMTA were found in either SEM or micro-CT analysis. In conclusion, pre-etching of apical dentin can provide a better seal for GMTA but not for WMTA.

Empirical evaluation of age groups and age-subgroup analyses in pediatric randomized trials and pediatric meta-analyses

BACKGROUND

An important step toward improvement of the conduct of pediatric clinical research is the standardization of the ages of children to be included in pediatric trials and the optimal age-subgroups to be analyzed.

METHODS

We set out to evaluate empirically the age ranges of children, and age-subgroup analyses thereof, reported in recent pediatric randomized clinical trials (RCTs) and meta-analyses. First, we screened 24 RCTs published in Pediatrics during the first 6 months of 2011; second, we screened 188 pediatric RCTs published in 2007 in the Cochrane Central Register of Controlled Trials; third, we screened 48 pediatric meta-analyses published in the Cochrane Database of Systematic Reviews in 2011. We extracted information on age ranges and age-subgroups considered and age-subgroup differences reported.

RESULTS

The age range of children in RCTs published in Pediatrics varied from 0.1 to 17.5 years (median age: 5; interquartile range: 1.8-10.2) and only 25% of those presented age-subgroup analyses. Large variability was also detected for age ranges in 188 RCTs from the Cochrane Central Register of Controlled Trials, and only 28 of those analyzed age-subgroups. Moreover, only 11 of 48 meta-analyses had age-subgroup analyses, and in 6 of those, only different studies were included. Furthermore, most of these observed differences were not beyond chance.

CONCLUSIONS

We observed large variability in the age ranges and age-subgroups of children included in recent pediatric trials and meta-analyses. Despite the limited available data, some age-subgroup differences were noted. The rationale for the selection of particular age-subgroups deserves further study.

Evaluation of mineral trioxide aggregate (MTA) versus calcium hydroxide cement (Dycal(®) ) in the formation of a dentine bridge: a randomised controlled trial

AIM

To assess the effectiveness of mineral trioxide aggregate (MTA) used as an indirect pulp-capping material in human molar and premolar teeth.

METHODOLOGY

We conducted a clinical evaluation of 60 teeth, which underwent an indirect pulp-capping procedure with either MTA or calcium hydroxide cement (Dycal(®) ). Calcium hydroxide was compared with MTA and the thickness of the newly formed dentine was measured at regular time intervals. The follow-up was at 3 and 6 months, and dentine formation was monitored by radiological measurements on digitised images using Mesurim Pro(®) software.

RESULTS

At 3 months, the clinical success rates of MTA and calcium hydroxide were 93% and 73%, respectively (P = 0.02). At 6 months, the success rate was 89.6% with MTA, and remained steady at 73% with calcium hydroxide (P = 0.63). The mean initial residual dentine thickness was 0.23 mm, and increased by 0.121 mm with MTA and by 0.136 mm with calcium hydroxide at 3 months. At 6 months, there was an increase of 0.235 mm with MTA and of 0.221 mm with calcium hydroxide.

CONCLUSIONS

  A higher success rate was observed in the MTA group relative to the Dycal(®) group after 3 months, which was statistically significant. After 6 months, no statistically significant difference was found in the dentine thickness between the two groups. Additional histological investigations are needed to support these findings.

Frequently asked questions in composite restorative dentistry

With an increasing number of dental practitioners using composite resins as the restorative material of choice, knowledge of terminology, handling properties and restorative techniques are important.

CLINICAL RELEVANCE

This paper addresses many of the questions raised by participants at lectures and courses given by the authors across Europe.

The effect of dentine-bonding agents on substance P release in human dental pulp

AIM

To quantify the effect of dentine-bonding agents on Substance P (SP) release in healthy human dental pulp tissue.

METHODOLOGY

Forty pulp samples were obtained from healthy pre-molars where extraction was indicated for orthodontic reasons. In thirty of these pre-molars, a standardized Class V cavity preparation was performed, and teeth were divided equally into three groups: (i) Unetched-cavity control group: Class V cavities only; (ii) Experimental Group I: 'One-step' self-etch bonding agent was placed in the cavity; and (iii) Experimental Group II: 'Two-step' total-etch bonding agent was placed in the cavity. The remaining ten healthy pre-molars where extracted without treatment and served as an intact-teeth control group. SP was measured by radioimmunoassay.

RESULTS

Greater SP release was found in the 'one-step' bonding agent group, followed by the 'two-step' bonding agent group and the unetched-cavity control group. The lower SP values were for the intact-teeth control group. anova showed statistically significant differences between groups (P = 0.0001). Tukey HSD post hoc tests showed statistically significant differences in SP release between the intact-teeth control group and the three other groups (P < 0.01) and between the unetched-cavity control group and the 'one-step' bonding agent group (P < 0.05). No significant difference was found between the 'two-step' bonding agent and the unetched-cavity control group.

CONCLUSION

Dentine-bonding agents placed over Class V cavity preparations increased SP release. One-step dentine-bonding agents increased SP release most.

Comparative cytotoxicity of five current dentin bonding agents: role of cell cycle deregulation

To compare the cytotoxicity of three nano-dentin bonding agents (nano-DBAs) and two non-nano-DBAs using Chinese hamster ovary (CHO-K1) cells. We found that nano fillers were not the major contributing factor in DBA cytotoxicity, as analyzed by colony forming assay and 3-(4,5-dimethyl-thiazol-2-yl)-2,5-diphenyl-tetrazolium bromide (MTT) assay. Exposure of CHO-K1 cells to all three tested total-etching DBAs led to G(0)/G(1) cell cycle arrest, whereas exposure to higher concentrations of two tested nano-DBAs induced G(2)/M arrest. All five DBAs further induced apoptosis at the highest concentration, as analyzed by propidium iodide staining flow cytometry. The toxicity of all DBAs (1:4000v/v or higher) is related to increased reactive oxygen species (ROS) production, as analyzed by single cell DCF fluorescence flow cytometry. These results indicate that clinical application of DBAs may be potentially toxic to dental pulp tissues. Cytotoxicity of DBAs is associated with ROS production, cell cycle deregulation and apoptosis. Presence of methacrylate monomers such as PENTA and UDMA is possibly the major cytotoxic factor for DBAs. Further studies on other toxicological endpoints of nano-DBAs are necessary to highlight their safe use.