Dentine permeability and its role in the pathobiology of dentine sensitivity

Diffusion of Silver Diamine Fluoride Solution in Dentine: An In Vitro Study

OBJECTIVES

The aim of this research was to assess the diffusion dynamics of silver and fluoride ions after 38% silver diamine fluoride (SDF) solution application on dentine of varying thicknesses over 24 weeks.

METHODS

Bovine dentine discs of 5.5 mm in diameter were prepared and separated into 3 groups with thicknesses of 0.5 mm (group 1), 1.0 mm (group 2), and 1.5 mm (group 3). The diameter and number of dentinal tubules of discs were assessed. Each disc received a topical application of 0.05 mL 38% SDF solution. The deionised water in the tube was collected weekly for 24 weeks. The silver and the fluoride ion concentrations in the collected deionised water were determined. Generalised estimating equations was used to explore the potential effects of the key factors on the silver/fluoride diffusion.

RESULTS

The amount of silver and fluoride ion diffusion through dentine almost levelled off after 4 weeks and showed a decline trend over 24 weeks. The mean (SD) 24-week cumulative ion diffusion through dentine in groups 1, 2, and 3 was as follows: 20 (4) μg, 10 (2) μg, and 5 (1) μg for silver (P < .05) and 18 (2) μg, 13 (2) μg, and 7 (1) μg for fluoride (P < .05), respectively.

CONCLUSIONS

Silver and fluoride ion diffusion through dentine showed a decline trend over 24 weeks. The diameter and the number of dentinal tubules on dentine with different thicknesses affects the ion diffusion dynamics. This study provides indications on the pattern of silver/fluoride ions diffusion through dentine to pulp after 38% SDF application. An increased amount of silver/fluoride diffuses through dentine into the pulp with decreased remaining dentine thickness.

The Amelogenin-Derived Peptide TVH-19 Promotes Dentinal Tubule Occlusion and Mineralization

In this study, the amelogenin-derived peptide, TVH-19, which has been confirmed to promote mineralization, was evaluated to derive its potential to induce dentinal tubule occlusion. The binding capability of fluorescein isothiocyanate (FITC)-labeled TVH-19 to the demineralized dentin surface was analyzed by confocal laser scanning microscopy (CLSM). Additionally, the sealing function of the peptide was studied through the remineralization of demineralized dentin in vitro. The adsorption results showed that TVH-19 could bind to the hydroxyapatite and demineralized dentin surfaces, especially to periodontal dentin. Scanning electron microscopy analysis further revealed that TVH-19 created mineral precipitates. The plugging rate in the TVH-19 group was higher than that in the PBS group. Moreover, energy-dispersive X-ray spectroscopy (EDX) results indicated that the calcium/phosphorus (Ca/P) ratio of the new minerals induced by TVH-19 was close to that of the hydroxyapatite. Attenuated total internal reflection-Fourier transform infrared (ATR-FTIR) spectrometry and X-ray diffraction (XRD) results indicated that the hydroxyapatite crystals formed via remineralization elongated the axial growth and closely resembled the natural dentin components. These findings indicate that TVH-19 can effectively promote dentin sealing by binding to the periodontal dentin, promoting mineral deposition, and reducing the space between the dentin tubules.

Assessment of the effect of experimental bleaching agent with nano-bioactive material on postoperative sensitivity: A randomized, triple blind clinical trial

OBJECTIVES

This clinical study aimed to evaluate the effect of incorporating bioactive nanoparticles (n-Bm) inside an in-office bleaching gel on the risk and intensity of tooth sensitivity (TS) and on bleaching effectiveness.

MATERIALS AND METHODS

Sixty-six participants were selected and randomly assigned into two groups: control-only in-office gel and experimental-in-office gel with n-Bm. Teeth were bleached in two sessions (3 × 15-min). TS was recorded using a VAS and NRS. The color change was evaluated by subjective (VITA Classical and VITA Bleachedguide) and objective (Easyshade spectrophotometer) methods at baseline and 30 days after the end of treatment. The TS was evaluated by McNemar, Wilcoxon Signed Rank, and paired t test. The color changes between groups were compared using paired t test (α = 0.05).

RESULTS

No significant differences between the groups were observed in the risk (control = 27% [95%IC 18-39]; experimental = 21% [95%IC 13-32]) and intensity of TS, as well as in the color change (p >0.05) for any color measurement.

CONCLUSION

The inclusion of n-Bm into the bleaching agents did not affect the whitening effectiveness, as well as the risk and intensity of TS between groups. However, the results of the absolute risk of TS were low for both in-office gels used.

CLINICAL SIGNIFICANCE

Despite no significant differences between groups, both experimental bleaching agents present suitable results with low values for TS.

Analysis of permeability and biological properties of dentin treated with experimental bioactive glasses

OBJECTIVES

To evaluate obliterating capability and biological performance of desensitizing agents.

METHODS

50 dentin blocks were distributed according to the desensitizing agent used (n = 10): Control (Artificial saliva); Ultra EZ (Ultradent); Desensibilize Nano P (FGM); T5-OH Bioactive Glass (Experimental solution); F18 Bioactive Glass (Experimental solution). Desensitizing treatments were performed for 15 days. In addition, specimens were subjected to acid challenge to simulate oral environment demineralizing conditions. Samples were subjected to permeability analysis before and after desensitizing procedures and acid challenge. Cytotoxicity analysis was performed by using Alamar Blue assay and complemented by total protein quantification by Pierce Bicinchoninic Acid assay at 15 min, 24-h and 48-h time points. Scanning electron microscopy and energy dispersion X-ray spectroscopy were performed for qualitative analysis. Data of dentin permeability was analyzed by two-way repeated measures ANOVA and Tukey's test. For cytotoxicity, Kruskal-Wallis and Newman-Keuls tests.

RESULTS

for dentin permeability there was no significant difference among desensitizing agents after treatment, but control group presented highest values (0.131 ± 0.076 Lp). After acid challenge, control group maintained highest values (0.044 ± 0.014 Lp) with significant difference to other groups, except for Desensibilize Nano P (0.037 ± 0.019 Lp). For cytotoxicity, there were no significant differences among groups.

CONCLUSION

Bioglass-based desensitizers caused similar effects to commercially available products, regarding permeability and dentin biological properties.

CLINICAL SIGNIFICANCE

There is no gold standard protocol for dentin sensitivity. The study of novel desensitizing agents that can obliterate dentinal tubules in a faster-acting and long-lasting way may help meet this clinical need.

In Vitro Evaluation of Desensitizing Agents Containing Bioactive Scaffolds of Nanofibers on Dentin Remineralization

This study evaluated the effect of the incorporation of bioactive nanofibers in desensitizing agents on dentin permeability. Sixty disks of dentin were randomly distributed in four groups (n = 15). Distribution was based on the desensitizing agents, fluoride varnish and self-etching adhesive, and the presence of nanofibers: C (self-etching adhesive Clearfil SE Bond), CN (Clearfil SE Bond with 1% nanofiber), D (Duraphat varnish), and DN (Duraphat varnish with 1% nanofiber). Dentin permeability was determined using hydraulic conductivity. For a qualitative analysis, confocal laser microscopy and scanning electron microscopy were performed. The C group showed the lowest hydraulic conductance (Lp%) (89.33), while the DN group showed the highest Lp% (116.06). No statistical significance was observed in the Lp% values in all groups after the treatment and 6% citric acid challenge (p > 0.239). In the images, the CN group presented a higher superficial and intratubular deposition. In addition, this group presented a more homogeneous dentin surface and wide occlusion of dentinal tubules than the other treatments. Despite there being no statistical differences among the treatments employed, the images showed that the CN group presented a higher surface and intratubular deposition compared to the other treatments, even after the acid challenge.

Acidic Monetite Complex Paste with Bleaching Property for In-depth Occlusion of Dentinal Tubules

Background

Dentin hypersensitivity (DH) is a common dental clinical condition presented with a short and sharp pain in response to physical and chemical stimuli. Currently no treatment regimen demonstrates long-lasting efficacy in treating DH, and unesthetic yellow tooth color is a concern to many patients with DH.

Aim

To develop a bi-functional material which can occlude dentinal tubules in-depth and remineralize dentin for long-lasting protection of the dentin–pulp complex from stimuli and bleach the tooth at the same time.

Methods

A mixture containing CaO, H₃PO₄, polyethylene glycol and H₂O₂ at a specific ratio was mechanically ground using a planetary ball. The mineralizing complex paste was characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Dentin was exposed to the synthesized paste for 8 h and 24 h in vitro. The mineralizing property was evaluated using SEM and microhardness tests. Red tea-stained tooth slices were exposed to the synthesized paste for 8 h and 24 h in vitro. The bleaching effect was characterized by a spectrophotometer.

Results

The complex paste had very a fine texture, was injectable, and had a gel-like property with 2.6 (mass/volume) % H₂O₂ concentration. The X-ray diffraction pattern showed that the inorganic phase was mainly monetite (CaHPO₄). The mineralizing complex paste induced the growth of inorganic crystals on the dentin surface and in-depth occlusion of dentin tubules by up to 80 μm. The regenerated crystals were integrated into the dentin tissue on the dentin surface and the wall of dentinal tubules with a microhardness of up to 126 MPa (versus 137 Mpa for dentin). The paste also bleached the stained dental slices.

Conclusion

The mineralizing complex paste is a promising innovative material for efficient DH management by remineralizing dentin and in-depth occlusion of dentin tubules, as well as tooth bleaching.

Crystal growth in dentinal tubules with bio-calcium carbonate-silica sourced from equisetum grass

BACKGROUND/PURPOSE

One effective way to deal with dentin hypersensitivity is to develop materials to seal the tubules. The porous bio-calcium carbonate-silica (BCCS) contained well-dispersed CaCO₃ would form calcium phosphates to seal the dentinal tubules when mixed with an acidic solution. The acidic hydrothermal treatment and calcination to isolate the BCCS from the agricultural waste like equisetum grass was used, which would be more environmentally friendly than chemically synthesized mesoporous biomaterials. The aim of this study was to develop mesoporous materials from natural resources to occlude the dentinal tubules which could be more environmentally-friendly.

METHODS

Dentin disc samples were prepared and treated with different methods as follows: (1) BCCS mixed with H₃PO₄; (2) BCCS mixed with KH₂PO₄; (3) Seal & Protect® was used as a comparison group. Sealing efficacy was evaluated by measuring the depths and percentages of precipitate occlusion in dentinal tubules with SEM.

RESULTS

The N₂ adsorption-desorption isotherm of the BCCS demonstrated a pore size of around 15.0 nm and a surface area of 61 m²g-1. From the results of occlusion percentage and depth, the BCCS treated with H₃PO₄ or KH₂PO₄ demonstrated promising sealing efficacy than the commercial product.

CONCLUSION

This synthetic process used the agricultural waste equisetum grass to produce bio-calcium carbonate-silica would be environmentally friendly, which has great potential in treating exposed dentin related diseases.

Novel calcium encapsulated mesocellular siliceous foams for crystal growth in dentinal tubules

OBJECTIVES

The aim of this study was to investigate the novel mesocellular siliceous foams (MCF) containing CaCO₃ nanoparticles (denoted as CMCF) combined with phosphoric acid could occlude dentinal tubules through the formation of biomimetic crystal barrier.

METHODS

Ultrastructures of MCF and CMCF were examined by transmission electron microscopy (TEM). Elemental components were analyzed with energy dispersive X-ray spectrometry (EDX). CMCF was mixed with distilled water, 10%, 20% and 30% phosphoric acid then applied on dentine discs. Crystals were characterized by X-ray powder diffractometry (XRD). The sealing efficacy of the dentinal tubules was examined by scanning electron microscopy.

RESULTS

TEM images showed MCF presented a pore size of approximately 30.0 nm and CMCF contained abundant nano-CaCO₃. Sealing efficacy showed that CMCF, when reacted with 30% phosphoric acid, would form crystals in the dentinal tubules to a depth of 83.2 ± 17.6 μm at an occlusion percentage of 75.6 ± 12.8% on average; both occlusion percentage and depth were higher than those obtained with 10% or 20% phosphoric acid (p < 0.05). The results of XRD and EDS indicated that the crystal growth in the dentinal tubules could be transformed into the biomimetic crystals.

CONCLUSION

This study showed that the CMCF with 30% phosphoric acid could effectively occlude the dentinal tubules through the formation of biomimetic crystal barrier.

CLINICAL SIGNIFICANCE

The novel CMCF combined with phosphoric acid may have potential for the treatment of dentine hypersensitivity.

The Effect of the Application Sequence of Casein Phosphopeptide-Amorphous Calcium Phosphate Paste on the Shear Bond Strength of Etch-and-Rinse Resin Cements to Dentin

PURPOSE

To evaluate the effect of the application sequence of casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) paste (MI paste) on shear bond strength (SBS) of 2 etch-and-rinse resin cements to dentin.

MATERIALS AND METHODS

Sixty extracted human maxillary premolars were cut to expose the mid-coronal dentin surfaces. The teeth were randomly divided into 6 groups (n = 10), based on the resin cement used and CPP-ACP application. In groups 1-3, Excite DSC/Variolink II and in groups 2-4, One-Step Plus/Duolink was bonded to dentin. There were 3 groups for each cement as follows: with no treatment as a control; 3-minute application of CPP-ACP before acid etching (CPP-ACP/Etching); 3-minute application of CPP-ACP after acid etching (Etching/CPP-ACP). After storage in distilled water at 37°C for 24 hours, SBS test was performed. Data were analyzed with 2-way ANOVA and post-hoc Tukey test (α = 0.05).

RESULTS

CPP-ACP application on the dentin before and after acid etching significantly decreased the SBS of OS/Duolink (13.60 and 14.71 MPa, respectively vs. control; 21.21 MPa, p < 0.001); however, it did not influence the SBS of Excite DSC/Variolink II (25.14 MPa) before acid etching (27.37 MPa) or after acid etching (26.41 MPa, p > 0.388). The application sequence of CPP-ACP did not influence the SBS of etch-and-rinse resin cements evaluated.

CONCLUSION

CPP-ACP applications may lower the SBS in some etch-and-rinse resin cements, and timing of applications makes no difference.

Dentin sealing and antibacterial effects of silver-doped bioactive glass/mesoporous silica nanocomposite: an in vitro study

OBJECTIVES

To synthesize a silver-doped bioactive glass/mesoporous silica nanoparticle (Ag-BGN@MSN), as well as to investigate its effects on dentinal tubule occlusion, microtensile bond strength (MTBS), and antibacterial activity.

MATERIALS AND METHODS

Ag-BGN@MSN was synthesized using a modified "quick alkali-mediated sol-gel" method. Demineralized tooth disc models were made and divided into four groups; the following treatments were then applied: group 1-no treatment, group 2-bioglass, group 3-MSN, group 4-Ag-BGN@MSN. Next, four discs were selected from each group and soaked into 6 wt% citric acid to test acid-resistant stability. Dentinal tubule occlusion, as well as the occlusion ratio, was observed using field-emission scanning electron microscopy. The MTBS was also measured to evaluate the desensitizing effect of the treatments. Cytotoxicity was examined using the MTT assay. Antibacterial activity was detected against Lactobacillus casei, and ion dissolution was evaluated using inductively coupled plasma optical emission spectrometry.

RESULTS

Ag-BGN@MSN effectively occluded the dentinal tubule and formed a membrane-like layer. After the acid challenge, Ag-BGN@MSN had the highest rate of dentinal tubule occlusion. There were no significant differences in MTBS among the four groups (P > 0.05). All concentrations of Ag-BGN@MSN used had a relative cell viability above 72%.

CONCLUSIONS

Ag-BGN@MSN was successfully fabricated using a modified sol-gel method. The Ag-BGN@MSN biocomposite effectively occluded dentinal with acid-resistant stability, did not decrease bond strength in self-etch adhesive system, had low cytotoxicity, and antibacterial effect.

CLININAL RELEVANCE

Dentinal tubule sealing induced by Ag-BGN@MSN biocomposite with antibacterial effect is likely to increase long-term stability in DH.

Effects of calcium-containing desensitizers on the bonding stability of an etch-and-rinse adhesive against long-term water storage and pH cycling

This study aimed to evaluate the effects of two calcium-containing desensitizing pastes on the bonding stability of an etch-and-rinse (E&R) adhesive to dentine. After dentine hypersensitivity model established, dentine surfaces were assigned one of the following pretreatment: Group 1, no desensitizer; Group 2, CPP-ACP; and Group 3, Novamin. Specimens were then bonded with an E&R adhesive. Beams from each tooth were randomly divided into three subgroups and then subjected to microtensile bond strength (MTBS) test after 24 h; 12 months of water storage; or 15 runs of pH cycling. Failure modes, nanoleakage, and tubule-occluding effectiveness were analyzed. Results showed that CPP-ACP- or Novamin-pretreated specimens mainly preserved the bonding strength after 12 months of water storage, while effective tubule occlusion could be observed. The results suggested that the calcium-containing desensitizers were compatible pretreatment for bonding with E&R adhesives to obtain reliable long-term bonding strength and prevention of post-operative sensitivity.

Development of Epigallocatechin-3-gallate-Encapsulated Nanohydroxyapatite/Mesoporous Silica for Therapeutic Management of Dentin Surface

In dental clinic, unsatisfactory management of the dentin surface after dentin exposure often leads to the occurrence of dentin hypersensitivity and caries. Current approaches can occlude the tubules on the dentin surface to relieve dentin hypersensitivity; however, the blocked tubules are generally weak in combating daily tooth erosion and abrasion. Moreover, cariogenic bacteria, such as Streptococcus mutans, produce biofilm on the dentin surface, causing caries and compromising the tubules' sealing efficacy. To overcome this problem, the present study focused on establishing a versatile biomaterial, epigallocatechin-3-gallate-encapsulated nanohydroxyapatite/mesoporous silica nanoparticle (EGCG@nHAp@MSN), for therapeutic management of the dentin surface. The effectiveness of the biomaterial on dentinal tubule occlusion, including resistances against acid and abrasion, was evaluated by field-emission scanning electron microscopy (FESEM) and dentin permeability measurement. The inhibitory capability of the biomaterial on S. mutans biofilm formation was investigated by confocal laser scanning microscopy (CLSM), 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, colony forming units (CFU) counts, and FESEM. Results demonstrated for the first time that the use of EGCG@nHAp@MSN on the dentin surface was capable of effectively occluding dentinal tubules, reducing dentin permeability, and achieving favorable acid- and abrasion-resistant stability. Furthermore, EGCG@nHAp@MSN held the capability to continuously release EGCG, Ca, and P, and significantly inhibit the formation and growth of S. mutans biofilm on the dentin surface. Thus, the development of EGCG@nHAp@MSN bridges the gap between multifunctional concept and dental clinical practice and is promising in providing dentists a therapeutic strategy for the management of the dentin surface to counter dentin hypersensitivity and caries.

The effect of a dentin desensitizer on the shear bond strength of composite to dentin using three different bonding agents: An in vitro study

Objective:

The effect of dentin desensitizer Systemp on the shear bond strength of composite resin to dentin using three different bonding agents, i.e., Prime & Bond NT, Xeno V⁺, and Futurabond DC were evaluated.

Materials and Methods:

Sixty recently extracted human premolars were divided into six groups of ten teeth each. The superficial dentin was etched with 37% phosphoric acid. In Groups I, II, and III, Prime & Bond NT, Xeno V⁺, and Futurabond DC, respectively, were applied to dentin and composite placed. Following application of dentin desensitizer Systemp in Groups IV, V, and VI, Prime & Bond NT, Xeno V⁺, and Futurabond DC, respectively, were applied to dentin and composite placed. The shear bond strength was evaluated. Data obtained were statistically analyzed using one-way analysis of variance, post hoc, and Dunnett's test.

Results:

Following application of dentin desensitizer Systemp, mean shear bond strength increased when Prime & Bond NT bonding agent was used while it decreased for Xeno V⁺ and Futurabond DC bonding agents.

Conclusion:

Within the limitations of this in vitro study, it was observed that following application of dentin desensitizer Systemp, mean shear bond strength may increase or decrease depending on the bonding agents used.

Effects of a Dicalcium and Tetracalcium Phosphate-Based Desensitizer on In Vitro Dentin Permeability

The present study evaluated the effectiveness of a dicalcium and tetracalcium phosphate-based desensitizer in reducing dentin permeability in vitro. Dentin fluid flow was measured before and after treatment of dentin with patent dentinal tubules using 1 or 3 applications of the dicalcium and tetracalcium phosphate containing agent TeethmateTM (TM) and comparing the results with two sodium fluoride varnishes VellaTM (VLA) and VanishTM (VAN), after storage in artificial saliva for 24 h, 48 h and 7 days. Significant differences were observed among the 4 methods employed for reducing dentin permeability (p < 0.001) and the 3 post-treatment times (p < 0.001). VLA and VAN never achieved 50% permeability reductions consistently in any of the 3 time periods. Only the calcium phosphate-based desensitizer applied for 3 times consistently reduced dentin permeability by 50% after 24 h. When applied once, the permeability reduction of TM increased progressively over the 3 time periods. After 7 days, only one and three applications of the calcium phosphate-based desensitizer consistently reduced dentin permeability by more than 50%. Permeability reductions corresponded well with scanning electron microscopy examination of dentinal tubule orifice occlusion in dentin specimens treated with the agents. Overall, the dicalcium and tetracalcium phosphate-based desensitizer is effective in reducing dentin permeability via a tubule occlusion mechanism. The ability of the agent to reduce dentin permeability renders it to be potentially useful as a clinical dentin desensitizing agent, which has to be confirmed in future clinical studies. By contrast, the two sodium fluoride varnishes are not effective in dentin permeability reduction and should be considered as topical fluoride delivering agents rather than tubular orifice-blocking agents.

Transdentinal cytotoxicity of resin-based luting cements to pulp cells

OBJECTIVES

The aim of this study was to evaluate the transdentinal cytotoxicity of components released from different resin-based luting cements to cultured MDPC-23 odontoblast-like cells and human dental pulp cells (HDPCs).

MATERIALS AND METHODS

Artificial pulp chamber (APC)/dentin disc sets were distributed into four groups according to the materials tested (n = 10), as follows: G1, control (no treatment); G2, resin-modified glass-ionomer cement (RelyX Luting 2); G3, self-adhesive resin cement (RelyX U200); and G4, conventional resin cement (RelyX ARC). The materials were applied to the occlusal surfaces (facing up) of the dentin discs adapted to the APCs. The pulpal surfaces of the discs were maintained in contact with culture medium. Then, an aliquot of 400 μL from the extract (culture medium + resin-based components that diffused through dentin) of each luting cement was applied for 24 h to HDPCs or MDPC-23 cells previously seeded in wells of 24-well plates. Cell viability analysis was performed by the MTT assay (1-way ANOVA/Tukey test; α = 5 %).

RESULTS

For MDPC-23 cells, RelyX ARC (G4) and RelyX Luting 2 (G2) caused greater reduction in cell viability compared with the negative control group (P < 0.05). Only the HDPCs exposed to RelyX ARC (G4) extract showed a tendency toward viability decrease (9.3 %); however, the values were statistically similar to those of the control group (G1) (P > 0.05).

CONCLUSIONS

In accordance with the safe limits of ISO 10993-5:1999 (E) recommendations, all resin-based luting cements evaluated in this study can be considered as non-toxic to pulp cells.

CLINICAL RELEVANCE

Cytotoxicity of resin-based luting cements is material-dependent, and the different protocols for the application of these dental materials to dentin may interfere with their cytotoxicity.

The iontophoresis of lignocaine with epinephrine into carious dentine for pain control during cavity preparation in human molars

OBJECTIVE

To determine the effectiveness of the iontophoretic delivery of lignocaine with epinephrine through carious dentine for pain control during cavity preparation.

DESIGN

The experiments were carried out on 56 carious molars that required class I restorations in 42 subjects (aged 15-20 years). The overhanging enamel and soft caries were removed then the sensitivity of the exposed dentine was tested with drilling, probing and air blast stimuli. The subject indicated the intensity of any pain produced by marking a visual analogue scale (VAS). The cavity was then filled with 20% w/v lidocaine with 0.1% w/v epinephrine and a 200 μA iontophoretic current applied for 2 min after which the sensitivity of the dentine was re-tested. If the dentine was not anaesthetized, the treatment and testing were repeated up to 6 times.

RESULTS

The total duration (min) of iontophoresis required to anaesthetize the dentine was: 2 in 7 teeth, 4 in 17 teeth, 6 in 14 teeth, 8 in 4 teeth, and 10 in 7 teeth. The remaining 7 teeth were not anaesthetized even after 14 min of iontophoresis.

CONCLUSIONS

The iontophoretic delivery of lignocaine with epinephrine anaesthetized dentine for cavity preparation in 49 of 56 (87.5%) of carious molars.

A novel potassium oxalate-containing tooth-desensitising mouthrinse: a comparative in vitro study

OBJECTIVE

To compare the efficacy of a new potassium oxalate (KO)-containing mouthrinse [Listerine® Advanced Defence Sensitive (LADS)] in reducing dentine permeability and occluding open dentinal tubules versus other desensitising products.

METHODS

The permeability of acid-etched dentine disks was measured by hydraulic conductance; dentine surfaces were examined by scanning electron microscopy and energy-dispersive X-ray spectroscopy. The KO concentration was optimised for tubule occlusion by screening formulations containing 0.0-2.0% KO (n=5 disks per concentration). The optimal formulation was compared with five commercial products with non-oxalate occlusion technologies. After establishing the baseline permeability of acid-etched dentine disks, disks (n=6 per product) were randomly treated with the desensitising products (12 treatments, each 60 s, alternated with distilled-water rinses) and permeability was measured at intervals. Occluded disks were acid challenged. All experiments were conducted at room temperature. An unpooled, two-tailed t test was performed to assess between-treatment differences in relative residual permeability.

RESULTS

The optimal concentration of KO in LADS was 1.4%, which provided ≈ 100% reduction in dentine permeability after nine treatments. Only LADS reduced permeability to zero and was significantly more effective in reducing dentine permeability than the other products (p ≤ 0.033 vs all other test products). All products partially occluded dentine. The occlusion associated with LADS was substantially more stable in resisting acid challenge versus Colgate® Sensitive Pro-Relief mouthrinse (p=0.054) and significantly more stable versus all other test products (p ≤ 0.045), as determined by dentine permeability.

CONCLUSION

LADS was significantly more effective in occluding open dentinal tubules versus other desensitising products.

CLINICAL SIGNIFICANCE

LADS provides fast, complete and stable intratubular occlusion of patent dentinal tubules.

Dentine sensitivity: past, present and future

OBJECTIVE

This review defines dentine sensitivity (DS), its prevalence, its aetiology, the mechanism(s) responsible for DS, its diagnosis and its treatment. The review then examines the modes of action of various treatments for DS including potassium salts, strontium salts, bioglasses, arginine/calcium carbonate and professional treatments such as adhesives and oxalates. The methods used to evaluate the various treatment modalities are discussed, including laboratory studies and randomised controlled clinical trials.

DATA SOURCES AND STUDY SELECTION

A literature search was conducted using PubMed, Ovid Medline and Cochrane reviews for information on DS and its treatments, as well as laboratory and clinical studies used to evaluate the efficacy of various DS treatments. With regard to efficacy of treatments for DS only reports of clinical studies that were randomised, controlled and blinded were reviewed. The authors offer new insights into the shortcomings of the recent systematic review of the use of oxalates for DS.

CONCLUSION

The authors introduce the concept of a novel desensitising mouthrinse containing 1.4% potassium oxalate: Listerine® Advanced Defence Sensitive mouthrinse. Readers of this supplement issue of the Journal of Dentistry are invited to review the significance of managing the clinical problem of DS. They are also invited to assess data from laboratory and randomised controlled clinical studies in order to understand the advantages offered by regular use of 1.4% potassium oxalate-containing mouthrinse, Listerine Advanced Defence Sensitive, in particular its resistance to daily erosive and/or abrasive challenges.

A clinical efficacy of 30% ethenolic extract of Indian propolis and Recaldent™ in management of dentinal hypersensitivity: A comparative randomized clinical trial

Objective:

The aim of this study is to evaluate the efficacy of 30% ethenolic extract of Indian propolis compared with Recaldent^™ (casein phosphopeptide-amorphous calcium phosphate) in reduction of dentinals hypersensitivity, a randomized, double-blind, split mouth, controlled clinical trial was conducted among the patients residing in Central Jail.

Materials and Methods:

A sample of 73 teeth from 13 patients having at least three teeth with dentinal hypersensitivity (DH) were randomly allocated into three treatment groups: Group A: 30% ethenolic extract of Indian propolis, Group B: Recaldent^™, Group C: Sterile water. Verbal rating scale was used to record the degree of hypersensitivity based on patient's response to tactile and air blast stimuli. The baseline scores were obtained. Each intervention group received applications of their respective agents consecutively on 1^st, 7^th, 14^th, and 21^st day. After each application the scores were recorded.

Results:

Both the 30% Indian propolis and Recaldent^™ showed significant reduction in DH.

Conclusion:

Recaldent^™ was found to be significantly better in reducing the DH compared to propolis and sterile water (P < 0.01).

Effects of the application sequence of calcium-containing desensitising pastes during etch-and-rinse adhesive restoration

OBJECTIVES

To evaluate the effects of different application sequence of calcium-containing desensitising pastes on bonding effectiveness and tubule occlusion during etch-and-rinse (E&R) adhesive restoration.

METHODS

Seventy molars were sectioned parallel to the occlusal plane, polished and randomly divided into seven groups (n=10). Group 1 was etched with 35% phosphoric acid for 15s. Groups 2-4 were treated with different calcium-containing desensitisers, including an arginine-calcium carbonate (Arg-CaCO3)-containing paste, a casein phosphopeptide-amorphous calcium phosphate (CPP-ACP)-containing paste and a calcium-sodium phosphosilicate (Novamin)-containing paste, respectively. Afterward, these groups were etched with 35% phosphoric acid for 15s. Groups 5-7 were initially etched and then treated with Arg-CaCO3-, CPP-ACP- and Novamin-containing desensitisers, respectively. In each group, samples were equally distributed into two subgroups (n=5) to bond with either a two-step E&R adhesive Adper SingleBond 2 (SB) or a three-step E&R adhesive Adper ScotchBond Multi-Purpose (SBMP). The microtensile bond strengths (MTBS) were tested and fracture modes were analyzed by stereomicroscopy and field-emission scanning electron microscopy (FESEM). Eight additional dentine disks were prepared to evaluate tubule occlusion prior to bonding using FESEM.

RESULTS

The application sequence of calcium-containing desensitising pastes did not significantly affect MTBS irrespective of two-step SB (P>0.05) or three-step SBMP E&R adhesives (P>0.05). Effective dentinal tubule occlusion was observed in the mode of etching-desensitising.

CONCLUSIONS

Applying calcium-containing desensitisers (particularly Arg-CaCO3- and Novamin-based) after etching during E&R adhesive restoration could achieve effective tubule occlusion without affecting the bonding strength.

Cytotoxicity evaluation of dentin contacting materials with dentin barrier test device using erbium-doped yttrium, aluminum, and garnet laser-treated dentin

Objectives:

The effect of dentin contacting materials on three-dimensional cultures of pulp-derived cells was evaluated in a dentin barrier test device using erbium-doped yttrium, aluminum, and garnet (Er:YAG) laser-treated dentin.

Methods:

The test materials (iBond®, G-Bond™, and Vitrebond™) were applied on laser-treated or untreated dentin discs. After 24 h of exposure with perfusion of the test chamber, cell survival was evaluated by enzyme activity and related to a nontoxic control material. The mean values of control tissues were set to represent 100% viability. Data were analyzed using Kruskal–Wallis and Mann–Whitney U test.

Results:

Vitrebond was the most toxic material for both laser-treated and untreated dentin. On untreated dentin, G-bond was cytotoxic to the pulp-derived cells ( p < 0.05), and iBond was similar to the negative control group ( p > 0.05). However, G-Bond and iBond were not cytotoxic when they were applied to Er:YAG laser-treated dentin ( p > 0.05).

Conclusion:

Er:YAG laser treatment of dentin may protect the pulp cells from toxic substances of dentin contacting restorative materials; however, this effect is material related. Taking into consideration the limitations of this in vitro study, the Er:YAG laser treatment of dentin before restoration might be an option for decreasing the cytotoxic effects of the dental materials. Further research is required for clinical applications.

Effects of Potassium Oxalate on Knoop Hardness of Etch-and-Rinse Adhesives

The objective of this study was to determine whether the hardness of etch-and-rinse adhesives may be affected by the pretreatment of acid-etched dentin with potassium oxalate desensitizer. Unerupted human third molars were cut into crown segments by removing the occlusal enamel and roots. The pulp chamber of these crown segments was connected to a syringe barrel filled with phosphate-buffered saline so that the moisture of dentin was maintained during the bonding procedures. Three etch-and-rinse adhesives—two two-step systems (Adper Single Bond 2 [SB], One-Step [OS]) and one three-step system (Adper Scotchbond Multi-Purpose [MP])—were applied to acid-etched dentin that had been treated (experimental groups) or not (control groups) with potassium oxalate (BisBlock). The Knoop hardness (KHN) of adhesives was taken at different sites of the outer surface of the adhesive-bonded dentin. The KHN of the three tested adhesives applied to acid-etched dentin treated with potassium oxalate was significantly lower than that exhibited by the respective controls (not treated with oxalate; p&lt;0.05). Regardless of the adhesive, the treatment with potassium oxalate reduced the adhesives' KHN (p&lt;0.05), with the OS system exhibiting the lowest KHN compared with the MP and SB systems.

Multi-component bioactive glasses of varying fluoride content for treating dentin hypersensitivity

OBJECTIVE

Dentin hypersensitivity (DH) is a commonly occurring dental condition, and bioactive glasses (BG) are used in dentifrice formulations for treating DH by forming a surface layer of hydroxycarbonate apatite (HCA) on the tooth, thereby occluding exposed dentinal tubules. Fluoride-containing BG, however, form fluorapatite, which is more stable toward acid attack, and provide a more sustainable option for treating DH.

METHODS

Melt-derived multi-component BG (SiO(2)-P(2)O(5)-CaO-CaF(2)-SrO-SrF(2)-ZnO-Na(2)O-K(2)O) with increasing CaF(2)+SrF(2) content (0-32.7 mol%) were prepared. Apatite formation, occlusion of dentinal tubules in dentin discs and ion release in Tris buffer were characterized in vitro over up to 7 days using X-ray diffraction, infrared spectroscopy, scanning electron microscopy and inductively coupled plasma emission spectroscopy.

RESULTS

The fluoride-containing bioactive glasses formed apatite from as early as 6h, while the fluoride-free control did not form apatite within 7 days. The glasses successfully occluded dentinal tubules by formation of apatite crystals and released ions such as fluoride, strontium and potassium.

SIGNIFICANCE

Fluoride significantly improved apatite formation of the BG, allowing for treatment of DH by occlusion of dentinal tubules. The BG also released therapeutically active ions, such as strontium and fluoride for caries prevention, zinc for bactericidal properties and potassium, which is used as a desensitizing agent in dentifrices.

Inflammatory mediators in fluid extracted from the coronal occlusal dentine of trimmed teeth

BACKGROUND

Chemokines and cytokines may occur in dentinal fluids in response to local infection and inflammation. To test this hypothesis, we assessed the presence and concentration of inflammatory mediators in fluid extracted from the coronal occlusal dentine of trimmed teeth.

DESIGN

Freshly extracted sound, carious, and restored molars were trimmed through the enamel to expose the underlying dentine, etched with 35% phosphoric acid, and rinsed. Fluid was extracted from the coronal occlusal dentine of these trimmed teeth by centrifugation at 2750 × g for 30 min.

RESULTS

When assessed by MALDI-TOF, fluid extracted from the coronal occlusal dentine from 16 molars contained at least 117 peaks with different masses suggesting that this fluid was rich with molecules within the appropriate mass range of potential mediators. Indeed, when assessed for chemokines and cytokines, fluid extracted from the coronal occlusal dentine from 25 extracted molars with caries lesions, 10 extracted restored molars with occlusal amalgam, and 77 extracted sound molars contained IL-1β, TNF-α, IL-6, IL-8, IL-12(p70), and IL-10. A significant elevation was found for TNF-α (p=0.041) in extracted fluid from teeth restored with amalgam fillings.

CONCLUSIONS

Overall, fluid extracted from the coronal occlusal dentine of trimmed teeth may be useful in identifying proteins and other molecules in dentine and pulpal fluids and determining their role as mediators in the pathogenesis of oral infection and inflammation.

Dentin hypersensitivity and oxalates: a systematic review

Treatment of dentin hypersensitivity with oxalates is common, but oxalate efficacy remains unclear. Our objective was to systematically review clinical trials reporting an oxalate treatment compared with no treatment or placebo with a dentin hypersensitivity outcome. Risk-of-bias assessment and data extraction were performed independently by two reviewers. Standardized mean differences (SMD) were estimated by random-effects meta-analysis. Of 677 unique citations, 12 studies with high risk-of-bias were included. The summary SMD for 3% monohydrogen-monopotassium oxalate (n = 8 studies) was -0.71 [95% Confidence Interval: -1.48, 0.06]. Other treatments, including 30% dipotassium oxalate (n = 1), 30% dipotassium oxalate plus 3% monohydrogen monopotassium oxalate (n = 3), 6% monohydrogen monopotassium oxalate (n = 1), 6.8% ferric oxalate (n = 1), and oxalate-containing resin (n = 1), also were not statistically significantly different from placebo treatments. With the possible exception of 3% monohydrogen monopotassium oxalate, available evidence currently does not support the recommendation of dentin hypersensitivity treatment with oxalates.

A Novel Mesoporous Biomaterial for Treating Dentin Hypersensitivity

An ideal material has yet to be discovered that can completely treat dentin hypersensitivity; however, calcium phosphate precipitation has exhibited potential value for the treatment of dentin hypersensitivity by the occlusion of dentinal tubules. We hypothesized that a novel mesoporous silica biomaterial (nano CaO@mesoporous silica, NCMS) containing nano-sized calcium oxide particles mixed with 30% phosphoric acid can efficiently occlude dentinal tubules and significantly reduce dentin permeability, even with the presence of pulpal pressure. This highly supersaturated Ca2+-and HPO4 2−ion-containing NCMS paste was brushed onto dentin surfaces, and the ions diffused deeply into the dentinal tubules and formed a CaHPO4·2H2O precipitation with a depth of 100 μm. The results of the dentin permeability tests showed that the novel mesoporous material exhibited a significant reduction in dentin permeability (p < 0.05), even under simulated pulpal pressure, as compared with our previously developed material, DP-bioglass, and a commercial desensitizing material, Seal & Protect®.

Dentine sealing provided by smear layer/smear plugs vs. adhesive resins/resin tags

The aim of this study was to evaluate the ability of five experimental resins, which ranged from hydrophobic to hydrophilic blends, to seal acid-etched dentine saturated with water or ethanol. The experimental resins (R1, R2, R3, R4, and R5) were evaluated as neat bonding agents (100% resin) or as solutions solvated with absolute ethanol (70% resin/30% ethanol). Fluid conductance was measured at 20 cm H(2)O hydrostatic pressure after sound dentine surfaces were: (i) covered with a smear layer; (ii) acid-etched; or (iii) bonded with neat or solvated resins, which were applied to acid-etched dentine saturated with water or ethanol. In general, the fluid conductance of resin-bonded dentine was significantly higher than that of smear layer-covered dentine. However, when the most hydrophobic neat resins (R1 and R2) were applied to acid-etched dentine saturated with ethanol, the fluid conductance was as low as that produced by smear layers. The fluid conductance of resin-bonded dentine saturated with ethanol was significantly lower than for resin bonded to water-saturated dentine, except for resin R4. Application of more hydrophobic resins may provide better sealing of acid-etched dentine if the substrate is saturated with ethanol instead of with water.

Oxalate-containing phytocomplexes as dentine desensitisers: An in vitro study

It is known that pulpal fluid movement through dentinal tubules causes dentinal hypersensitivity and that pain can be reduced by decreasing the fluid flow. The aim of this study was to evaluate dentinal permeability and morphology after a single exposure to experimental phytocomplex substances containing oxalates. The treatments tested were experimental pastes, gels and solutions of phytocomplexes (extracted from rhubarb, spinach and mint), an experimental paste containing 5% potassium oxalate, and two commercial toothpastes recommended for dentinal hypersensitivity (Elmex and Sensodyne). Dentine discs from human third molars were used in this study. Each sample was brushed for 3 min with each treatment in order to test reductions in dentinal permeability. Each treated sample was challenged with orthophosphoric acid for 90 s to determine changes in dentinal permeability and the sensitivity of treatments to acid challenge. Scanning electron microscopy was used to analyse the samples. This study found that spinach and rhubarb phytocomplex treatments reduced dentinal permeability by occluding dentinal tubules through formation of calcium oxalate crystals. These results indicate that phytocomplexes extracted from rhubarb and spinach, used in different formulations, should be effective for topical treatment of dentinal hypersensitivity.

Effects of Er:YAG and Nd:YAG lasers on dentin permeability in root surfaces: a preliminary in vitro study

OBJECTIVE

This in vitro study evaluated the effects of Nd:YAG and Er:YAG lasers on reducing dentin permeability by sealing opened tubules.

BACKGROUND DATA

According to hydrodynamic theory, dentine hypersensitivity occurs when dentin is exposed with tubules opened. Consequently, a painful sensation occurs due to an intensification of the dentinal permeability. Treatment, therefore, should be based on a decrease of this permeability, achieved by the obliteration of dentinal tubules. The Nd:YAG laser is known for its capacity to seal dentinal tubules; however, few studies concerning treatment with Er:YAG laser are available.

METHODS

The Nd:YAG laser was used, based on two parameters: (A) 1.0 W, 10 Hz, and (B) 1.5 W, 15 Hz. The Er:YAG laser was used at 60 mJ, 2 Hz, four applications of 20 sec each, at 6 mm from the surface. After irradiation, all samples were immersed in 1% Rodamine B dye solution, in order to evaluate the penetration of the dye solution and observe the decrease/increase of dentinal permeability after the laser treatment.

RESULTS

The laser conditions used in the present study decreased the permeability as follows: (a) when using the Er:YAG laser at 60 mJ, 2 Hz in 26.05%, and (b) when using the Nd:YAG laser at 1.5 W, 15 Hz in 19.03%--with no statistical difference between them. Additionally, the Nd:YAG laser at 1.0 W, 10 Hz, decreased permeability in 4.59%, with a smaller effect.

CONCLUSIONS

According to the results of this in vitro study, the Er:YAG laser at 60 mJ, 2 Hz, and the Nd:YAG laser at 1.5 W, 15 Hz are useful for decreasing dentin permeability.

Cloning and Functional Study of Porcine Parotid Hormone, a Novel Proline-rich Protein

A parotid gland hormone that stimulates intradentinal fluid movement is believed to play a significant role in maintaining the vitality of dentin. This hormone has been purified from porcine parotid glands and partially sequenced in our previous study (Tieche, J. M., Leonora, J., and Steinman, R. R. (1980) Endocrinology 106, 1994-2005). We now report the cloning and functional study of porcine cDNAs that code for this hormone and its complete amino acid sequence. Three cDNA clones were isolated from a porcine parotid cDNA library. The last 30 amino acids encoded by two of the cDNAs agreed with the amino acid sequence of the isolated parotid hormone. In situ hybridization and immunohistochemical staining demonstrated that the acinar cells of the parotid glands were the primary location for both the parotid hormone-related mRNAs and the translation products. A 216-bp fragment of the cDNA that contains the coding sequence for the porcine hormone was subcloned into an expression vector, and the protein expression was detected by immunoblot analysis and quantified by enzyme-linked immunosorbent assay. In addition, the 30-amino acid parotid hormone was synthesized. Both the expressed and the synthetic proteins were biologically active in that they enhanced intradentinal fluid movement as measured by intradentinal dye penetration.

A Morphologicalin VitroStudy of the Effects of Nd:YAG Laser on Irradiated Cervical Dentin

OBJECTIVE

The purpose of this in vitro study was to verify the efficacy of Nd:YAG pulsed laser at 1064 nm in sealing dentinal tubules in vitro, with its resulting morphological changes using clinical parameters applicable to the treatment of dentin hypersensitivity.

BACKGROUND DATA

Although many papers have been written on the subject, no rapid, efficient, and long-lasting treatment for this problem has been developed.

MATERIALS AND METHODS

Twenty healthy extracted human teeth were kept in saline solution. Cervical cement was removed with a no. 57FG bur to expose approximately 4 mm(2) of dentin. Two groups were in the buccal aspect (A and B-irradiated) and one group in the lingual aspect (C-control not irradiated) of the same tooth. Samples with a remaining dentinal thickness between 1 and 1.5 mm were selected. Irradiation parameters were 30 mJ, 0.3W(Group A) and 40 mJ, 0.4 W(Group B); 7 Hz was used in both groups in two 43-sec applications each, with a 10-sec interval. In 10 samples, the dentinal surface underwent SEM examination for study. The other 10 remaining irradiated samples were centrally cleaved to study laser penetration depth in dentin (SEM).

RESULTS

Obliteration of dentinal tubule openings and solidification of the dentin surface were observed in all irradiated samples. Laser penetration depth in dentin (SEM) varied from 1 to 7 microm, depending on irradiation parameters used in each group.

CONCLUSION

We concluded that the use of the Nd:YAG laser was a very effective measure for obliterating dentinal tubule openings.

Occlusion of dentinal tubules and selective block of pulp innervation prevent the nociceptive behaviour induced in rats by intradental application of irritants

OBJECTIVES

Application of irritants on the exposed dentine of the incisors has been shown to produce aversive behaviour in awake rats. This study aims to demonstrate that the observed aversion is due to the infiltration of irritants through the dentinal tubules and the activation of capsaicin sensitive fibres in the tooth pulp.

METHODS

Different groups of rats were subjected, under anaesthesia, to cutting of the distal 2 mm of their lower incisors and the fixation of an artificial crown that allows the application of 10-15 microl of solution. Several procedures were followed to prevent the action of the irritants including occlusion of the dentinal tubules, local application of lidocaine, selective ablation of the capsaicin sensitive primary afferents (CSPA) or incisor pulpectomy; the reactions to intradental application of either capsaicin (1%) or formalin (2.5%) were tested using a newly designed behavioural score.

RESULTS

Occlusion of dentinal tubules produced significant attenuation of the nociceptive behaviour induced by dentinal application of either capsaicin or formalin. Similar results were observed following either local block with lidocaine (2%), selective ablation of capsaicin sensitive afferents or total denervation by pulpectomy.

CONCLUSIONS

The present results confirm the hypothesis of infiltration of irritants to the incisor pulp through the dentinal tubules and suggest that the reported inflammatory reaction and hyperalgesia are mediated, to a large extent, by capsaicin sensitive primary afferents.

In vivo sensitivity of human root dentin to air blast and scratching

BACKGROUND

The present study evaluated the prevalence of radicular sensitivity to scratching as well as the effects of a common oxalate desensitizing agent on sensitivity to air blast and scratching.

METHODS

Eighty-seven patients self-reporting dentin hypersensitivity, with at least two hypersensitive teeth, were included. Prior to any treatment, their sensitivity to air blast was recorded and rated as absent or present, and the force necessary to trigger pain when scratching was measured with a scratchometer in cN. For each patient one sensitive tooth was treated with an oxalate desensitizing agent and the other one with a placebo solution. The same measurements were carried out after treatment.

RESULTS

Following treatment with a placebo solution, 70% of the teeth remained sensitive to air blast while only 38% of the desensitizing agent-treated teeth remained sensitive to air blast (P < 0.01). The mean force required to elicit pain prior to any treatment was 44 +/- 17 cN. This force statistically increased significantly after application of the placebo (53 +/- 17 cN) (P < 0.05). After using the desensitizing agent, the force was even higher (95 +/- 24 cN) (P < 0.01). Only 8% of the teeth treated with the desensitizing agent did not respond to treatment compared to 37% of the teeth treated with the placebo solution.

CONCLUSIONS

The placebo solution had a significant effect on sensitivity to air blast and to scratching (P < 0.05). The oxalate desensitizing agent was more effective than the placebo solution at decreasing the sensitivity both to air blast and to scratching (P < 0.01). The sensitivity to air blast seems to be overestimated because, after using the desensitizing agent, 38% of the teeth remained sensitive to air blast but only 8% remained sensitive to scratching. Pulpal inflammation may be involved in those teeth that did not respond to treatment.

Pulpal space pressure and temperature changes from Nd:YAG laser irradiation of dentin

OBJECTIVES

To investigate pulpal space pressure and temperature after application of Nd:YAG laser, and high-speed diamond bur on dentin surface.

METHODS

One and 3 W Nd:YAG laser and high-speed diamond bur were used to remove dentine from twenty extracted premolars. The pulp chambers were monitored for pressure and temperature changes with a pressure transducer and thermocouple, respectively.

RESULTS

Regardless of the remaining dentin thickness (RDT), laser irradiation and high-speed diamond bur use generated an increase in pulpal space pressure and temperature (ANOVA and Fisher's LSD tests, P < 0.001). Pressure and temperature increased with an increase in laser power. Three-Watt laser irradiation caused greater changes than 1 W (1.75 kPa and 1.31 degrees C, 0.53 kPa and 0.34 degrees C, respectively). Both pulpal space pressure (P < 0.001) and temperature (P < 0.005) increased as the RDT decreased.

CONCLUSIONS

Laser irradiation and the use of a high-speed diamond bur generated an increase in pulpal space pressure and temperature. Pulpal space pressure and temperature increased with an increase in energy density of laser and a decrease in RDT.

Infectious complications of dental and periodontal diseases in the elderly population

Retention of teeth into advanced age makes caries and periodontitis lifelong concerns. Dental caries occurs when acidic metabolites of oral streptococci dissolve enamel and dentin. Dissolution progresses to cavitation and, if untreated, to bacterial invasion of dental pulp, whereby oral bacteria access the bloodstream. Oral organisms have been linked to infections of the endocardium, meninges, mediastinum, vertebrae, hepatobiliary system, and prosthetic joints. Periodontitis is a pathogen-specific, lytic inflammatory reaction to dental plaque that degrades the tooth attachment. Periodontal disease is more severe and less readily controlled in people with diabetes; impaired glycemic control may exacerbate host response. Aspiration of oropharyngeal (including periodontal) pathogens is the dominant cause of nursing home-acquired pneumonia; factors reflecting poor oral health strongly correlate with increased risk of developing aspiration pneumonia. Bloodborne periodontopathic organisms may play a role in atherosclerosis. Daily oral hygiene practice and receipt of regular dental care are cost-effective means for minimizing morbidity of oral infections and their nonoral sequelae.

Influence of a simulated oral environment on microleakage of two adhesive systems in Class II composite restorations

OBJECTIVES

The aim of this in vitro study was to evaluate the influence of a simulation of intra-oral conditions on the microleakage of two adhesive systems (Scotchbond MultiPurpose Plus=SBMP+ and Clearfil SE Bond=SE Bond). For SBMP+, the influence of bonding procedure (comparison between manufacturer's protocol and an experimental procedure) was also studied.

METHODS

Sixty Class II cavities with cervical margins 1mm below the cemento-enamel junction were prepared in the mesial/distal surfaces of recently extracted human molars. For the 3 groups (n=10), the adhesive system was applied under ambient conditions (20 degrees C/40% of relative humidity (RH)) for the mesial cavity and under extreme conditions (35 degrees C/95% RH) for the distal cavity. SBMP+ and SE Bond were applied strictly according to manufacturer's instructions. SBMP+ was also used according to an experimental procedure (intensive evaporation of the primer solvent). Cavities were restored with Z 100. After polishing, the specimens were thermocycled (2000 cycles, 5-55 degrees C). Teeth were coated with nail varnish, immersed in silver nitrate and sectioned longitudinally. The extent of microleakage was measured in percentage of dye penetration. Statistical analysis was performed using a 2 way ANOVA and a Fischer's PLSD test.

RESULTS

Microleakage was dependent on the environmental conditions. In '35 degrees C/95% RH' conditions, dye penetration significantly increased for the 3 groups. For SE Bond, the microleakage percentages were the lowest, both in ambient and extreme conditions. For SBMP+, the experimental procedure allowed a decrease in microleakage, but only in ambient conditions.

CONCLUSIONS

The simulation of intra-oral conditions caused a large increase in microleakage in the 3 groups tested. The self-etching primer presented the best behavior towards the 'temperature/RH' parameters simulated in this study.

A perfusion technique for the determination of pro-inflammatory mediators induced by intradental application of irritants

INTRODUCTION

Several morphological and functional features contribute to the consideration of the tooth as a separate compartment having special type of innervation and special immune mechanisms. This study describes a new method allowing the intradental perfusion of rat incisors for the in vivo assessment of pulpal reaction to inflammatory agents.

METHODS

Under deep anesthesia, the distal 2-3 mm of each of the rat lower incisors was cut and wrapped in a polyethylene tubing connected to a perfusion chamber made of tigone tubing (ID 1/8 in., volume 100-150 microl). Several groups of rats (n=5 each) were used for intradental application of either saline, capsaicin (100 microg in 100 microl), or endotoxin (ET, 20 microg in 100 microl) for a period of 40 min followed by filling the tooth chamber with saline and collecting the perfusate every 40 min for a period of 8 h. The collected perfusates were stored at -70 degrees C for subsequent determination of the concentration of prostaglandin E(2) (PGE(2)) and nerve growth factor (NGF) by enzyme-linked immunosorbent assay (ELISA).

RESULTS

Dentinal injury produced a moderate increase in the levels of NGF and PGE(2) in incisors perfused with saline. Application of ET or capsaicin, however, produced a highly significant increase in the levels of both mediators. These effects peaked at 1.5-3 h for PGE(2) and at 5 h for NGF. Capsaicin showed the most significant effects.

DISCUSSION

The reported results cannot be attributed to any factor other than the inflammation of the incisor's pulp, because the described chamber does not allow any spread or leak of the applied irritants. Further studies using other reagents can allow the determination of the variation of the levels of the various pro-inflammatory mediators and their modulation by treatment with anti-inflammatory drugs.

Clinical evaluation of wound healing following multiple exposures to enamel matrix protein derivative in the treatment of intrabony periodontal defects

BACKGROUND

Multiple exposures to enamel matrix protein derivative (EMD) during periodontal therapy have been shown to be safe for the patient. The purpose of this study was to clinically determine if an altered course of wound healing would occur after multiple exposures to EMD in the treatment of intrabony defects. A secondary aim was to assess the efficacy of EMD in probing depth reduction and clinical attachment level gain.

METHODS

Thirty-two systemically healthy patients (18 females, 14 males, 33 to 69 years old) who were being treated for moderate to advanced periodontal disease were selected for the study. Surgical procedures involving 2 sites were separated by at least 8 weeks, and wound healing comparisons were made between the first and second procedure. Patients were given a diary card the day of surgery, which consisted of questions concerning the presence and severity of headaches, root hypersensitivity, tooth pain, swelling, and itching. Patients were also examined at postoperative visits to clinically assess wound healing and discuss responses to the questionnaire. Soft tissue measurements were taken the day of surgery and 6 months postoperatively to ascertain probing depth reduction (PD) and gains in clinical attachment levels (CAL).

RESULTS

The results revealed no clinically detectable reaction that could not be attributed to normal postoperative sequelae. There were no differences in reported symptoms between patient gender, first and second procedures, or intrabony and non-intrabony defects. Smokers were found to have a statistically significantly higher incidence of severe symptoms in root hypersensitivity, tooth pain, and swelling compared to non-smokers (n = 21). The mean probing depth reduction was 3.8 +/- 1.5 mm (2 to 9 mm), while the mean clinical attachment level gain was 2.8 +/- 1.7 mm (0 to 8 mm).

CONCLUSIONS

The findings of this study demonstrate that EMD is a clinically safe product to use in the treatment of periodontal defects and that multiple uses do not have a negative impact on periodontal wound healing. In addition, a statistically significant gain in clinical attachment and reduction in probing depth were demonstrated.