Spectrophotometric analysis of the effectiveness of different dentin tubule occlusion techniques in preventing discoloration caused by photosensitizers used in photodynamic therapy

AIM

The efficacy of Copal Varnish (CV), dentin bonding agent (DBA), Nd:YAG laser and Er:YAG laser, which occludes dentin tubules by different mechanisms, was investigated in order to prevent unwanted coloration caused by methylene blue (MB) and phthalocyanine used in photodynamic therapy (PDT).

MATERIALS AND METHODS

165 upper incisors included in the study. Root canals were prepared up to 30/0.6 size for all teeth using Protaper Next rotary files. Then the teeth were randomly divided into 2 main groups (n = 60); MB and phthalocyanine. Each main group was randomly divided into 5 subgroups (n = 15); Positive control, DBA, CV, Er:YAG and Nd:YAG. Root canals were filled with photosensitizers (PS) and activated after the dentin tubule occlusion method was applied to all teeth. Then, the residual PSs were removed by irrigation. Color measurements of the samples were carried out 5 different time periods.

RESULTS

Clinically detectable color change was observed in all groups except for the negative control (ΔE≥3.3). It was determined that the positive control using MB caused more unwanted coloration in the CV on the 30th and 90th days compared to the phthalocyanine used in the 90th day (p < 0.05). While none of the dentin tubule occlusion methods were superior to each other in preventing undesirable coloration caused by phthalocyanine, Er:YAG caused less unwanetd coloration than CV only on the 90th day in preventing unwanted coloration caused by MB (p < 0.05).

CONCLUSIONS

All dentin tubule occlusion methods used in the present study were effective in preventing some degree of unwanted discoloration. However, it was found that no technique could completely prevent unwanted coloration.

Epigallocatechin-3-gallate/mineralization precursors co-delivery hollow mesoporous nanosystem for synergistic manipulation of dentin exposure

As a global public health focus, oral health plays a vital role in facilitating overall health. Defected teeth characterized by exposure of dentin generally increase the risk of aggravating oral diseases. The exposed dentinal tubules provide channels for irritants and bacterial invasion, leading to dentin hypersensitivity and even pulp inflammation. Cariogenic bacterial adhesion and biofilm formation on dentin are responsible for tooth demineralization and caries. It remains a clinical challenge to achieve the integration of tubule occlusion, collagen mineralization, and antibiofilm functions for managing exposed dentin. To address this issue, an epigallocatechin-3-gallate (EGCG) and poly(allylamine)-stabilized amorphous calcium phosphate (PAH-ACP) co-delivery hollow mesoporous silica (HMS) nanosystem (E/PA@HMS) was herein developed. The application of E/PA@HMS effectively occluded the dentinal tubules with acid- and abrasion-resistant stability and inhibited the biofilm formation of Streptococcus mutans. Intrafibrillar mineralization of collagen fibrils and remineralization of demineralized dentin were induced by E/PA@HMS. The odontogenic differentiation and mineralization of dental pulp cells with high biocompatibility were also promoted. Animal experiments showed that E/PA@HMS durably sealed the tubules and inhibited biofilm growth up to 14 days. Thus, the development of the E/PA@HMS nanosystem provides promising benefits for protecting exposed dentin through the coordinated manipulation of dentin caries and hypersensitivity.

The ability of a potassium oxalate gel strip to occlude human dentine tubules; a Novel in vitro: In situ Study

OBJECTIVES

To determine if an oxalate strip reduced fluid flow in dentine samples and whether this reduction was maintained following a 14 day intra-oral period.

METHODS

Dentine tubule fluid flow was measured by a modified Pashley cell in 40 acid-etched dentine discs 1 mm thick, diameter >10 mm, with an acquired pellicle, pre-equilibrated with Hartmann's solution and conditioned by toothbrushing, pre and post treatment (10 min) with an oxalate (3.14 %) gel strip or no treatment. One control and one test sample were exposed in-situ for 14 days to the oral environment in 20 healthy adult volunteers, and fluid flow re-measured. The appliance containing the two samples was removed for brushing with water after mealtimes when the participant brushed their teeth and for a 2 min daily soak in chlorhexidine.

RESULTS

Fluid flow rate was reduced significantly immediately following treatment with the oxalate strip compared to baseline flow rate by 58 %. Following 14 days in-situ oral environment phase, a significant further reduction in fluid flow compared to baseline was identified in both control and oxalate strip treated samples, both (p < 0.0001), but the reduction was greater in the test samples, 94 % vs 87 %, p < 0.01.

CONCLUSIONS

This novel investigation is the first to show fluid flow measurement using the Pashley model in dentine samples that have been housed in the mouth for 14 days. Treatment with an oxalate strip designed for dentine hypersensitivity alleviation reduced dentine fluid flow more than control providing evidence that the oxalate treatment withstood the oral environment over a prolonged time.

CLINICAL SIGNIFICANCE

This study demonstrated the efficacy and durability of the oxalate precipitate over a 14 day period in achieving and maintaining dentine tubule occlusion when participants had no dietary restrictions. This demonstrates the suitability of the oxalate strip for the treatment of patients suffering from dentine hypersensitivity pain.

Influence of desensitizing and anti-erosive toothpastes on dentine permeability: An in vitro study

OBJECTIVE

This study analyzed the effect of desensitizing and/or anti-erosive toothpastes on dentine permeability.

METHODS

One-mm dentin discs were prepared from human molars and exposed to EDTA solution (5 min, 17%). Initial dentine permeability was measured, under constant pressure. Specimens were randomly allocated into 10 groups: four anti-erosive toothpastes (calcium silicate + sodium phosphate, potassium nitrate, stannous chloride + chitosan, oligopeptide-104); four desensitizing toothpastes (arginine + calcium carbonate, calcium sodium phosphosilicate, strontium acetate, stannous fluoride); and two controls (regular fluoridated toothpaste, and human saliva). They were submitted to a 5-day erosion-abrasion cycling model. Erosion consisted of immersion in citric acid (2 min, 0.3%, natural pH ˜ 2.6, 4x/day), followed by 1 h exposure to human saliva. Specimens were brushed for 15 s (2 N, 45 strokes) with the toothpaste slurries (total exposure time of 2 min). After 5 cycles, the final dentine permeability was determined. Dentine permeability change was calculated as a percentage of the initial hydraulic conductance (%Lp). Data were analyzed with one-way ANOVA and Tukey tests (α=0.05).

RESULTS

The toothpastes calcium silicate + sodium phosphate and potassium nitrate, showed significant decrease in %Lp, with no difference between them. The regular fluoridated toothpaste also decreased the %Lp, not differing from potassium nitrate. No desensitizing toothpaste showed change in %Lp. Human saliva, oligopeptide-104 and stannous chloride + chitosan presented significant increase in %Lp, without difference between them.

CONCLUSION

Calcium silicate + sodium phosphate, potassium nitrate, and the regular fluoridated toothpaste decreased dentine permeability, whereas the desensitizing toothpastes tested did not.

CLINICAL RELEVANCE

Toothpastes had distinct impacts on dentine permeability, which may reflect a variable effect on the treatment of dentine hypersensitivity. Within the limitations of a laboratory-based study, toothpastes with an anti-erosive claim could also be effective in reducing the pain in dentine hypersensitivity.

Clinical Efficacy in Relieving Dentin Hypersensitivity of Nanohydroxyapatite-containing Cream: A Randomized Controlled Trial

Objective:

The study aimed to investigate the effectiveness of Apadent Pro (Sangi) Nanohydroxyapatite (nHAP) dental cream to relieve Dentin Hypersensitivity (DHS), compared with a positive control cream containing 20% pure silica (Silica).

Methods:

In this double-blind, randomized, parallel-group clinical trial, patients diagnosed with DHS and qualified to participate were randomized into two groups, nHAP (n=25) and Silica (n=26). Subjects’ baseline and posttreatment sensitivity were assessed using two pain scales, a four-point Dental Pain Scale (DPS) followed by a linear Visual Analog Scale (VAS), after the application of ice-cold and air stimuli. Subjects used custom-fabricated trays to apply their respective cream for 5 minutes once daily following brushing with standard fluoride toothpaste. Posttreatment sensitivity (efficacy) was assessed every 2 weeks for 8 weeks. Mean treatment outcomes (percentage change from baseline) at each time point were compared using the Tukey HSD test for multiplicity (P<0.05).

Results:

With either air or cold stimulus, VAS and DPS indicated a significant (P<0.001) reduction in DHS at each time point with either nHAP or Silica. Comparing pain scales, VAS showed no significant difference in DHS reduction between the products with either air or cold. However, with DPS, DHS reduction was significantly (P<0.05) better with Silica than with nHAP at all time points with cold, and at 2, 4, and 8 weeks with air.

Conclusion:

Both Apadent Pro nHAP and Silica dental creams are effective at promoting the relief of DHS symptoms. When comparing the efficacy of the two compounds to relieve DHS, results of the two pain scales were conflicting.

Dentinal Tubule Occluding Effect of Potassium Nitrate in Varied Forms, Frequencies and Duration: An In vitro SEM Analysis

INTRODUCTION

Dentinal hypersensitivity is an exaggerated response to non-noxious sensory stimuli (osmotic, thermal or mechanical changes). An inverse relationship between occluding open tubules and the intensity of sensitivity has been reported. Studies on the efficacy of potassium nitrate used in different forms and frequencies to occlude dentinal tubules are scarce.

AIM

To evaluate, in vitro the dentinal tubule occluding effect of potassium nitrate which differ in form, frequency and duration of application.

MATERIALS AND METHODS

In an in vitro study, 45 extracted human maxillary and mandibular premolars were sectioned using diamond disc to obtain 90 samples which were treated with 6% citric acid and were randomly assigned to three groups: Group 1 was treated with potassium nitrate toothpaste (once and twice daily for two minutes); Group 2 with potassium nitrate mouthwash (once and twice daily for two minutes) and Group 3 served as control (distilled water). Post-treatment, the samples were immersed in distilled water. The samples were subjected to Scanning Electron Microscopy (SEM) at the end of 3, 7 and 14 days. SEM photographs were analysed based on extent of tubular occlusion. Chi-square test was applied to assess the significant difference between the groups.

RESULTS

There was detectable difference in the dentinal tubule occlusion at the end of 3^rd, 7^th and 14^th day between three groups. When compared to the mouthwash, toothpaste yielded better results. Twice daily application for a period of two minutes each was better when compared to once daily for two minutes.

CONCLUSION

Potassium nitrate is effective in occluding dentinal tubules when applied twice daily in toothpaste form than mouthwash form. However, randomised control trials are needed to confirm its efficacy in human subjects.

Randomised clinical trial to evaluate changes in dentine tubule occlusion following 4 weeks use of an occluding toothpaste

Objectives

The objective of this study is to determine whether a silicone impression material could precisely replicate dentine tubule changes following 4 weeks toothbrushing with occluding or non-occluding toothpaste and whether changes reflected hypersensitivity clinical assessment.

Materials and methods

This was a single site, examiner blind, parallel, two treatment arm, randomised clinical trial. Participants were healthy, ≥18, with ≥1 sensitive tooth with exposed dentine, Schiff sensitivity score ≥2, and patent tubules with dentine occlusion score 4–5 as determined by scanning electron microscopy of replica impressions. Nine participants received Sensodyne® Rapid Relief (occluding toothpaste) and 10 Crest® Decay Prevention (non-occluding toothpaste), and were re-evaluated for sensitivity and occlusion score after two timed minutes and 4 weeks twice-daily home brushing.

Results

Occlusion scores did not correlate significantly with pain scores, but correlations were positive and impressions showed characteristic dentine tubule patency and occlusion. After 4 weeks, thermal VAS was significantly lower than baseline for the non-occluding toothpaste; all other pain scores were significantly lower for both treatments. Dentine occlusion scores also decreased after 4 weeks of either treatment, but did not achieve significance (p = 0.0625).

Conclusions

Both toothpastes reduced clinical sensitivity and increased tubule occlusion. It is hypothesised that during impression, taking some material may have sheared off and occluded tubules resulting in false positives.

Clinical relevance

This study has demonstrated that a silicone impression material can accurately replicate the dentine surface to demonstrate dentine tubular occlusion and patency; however, although the association between occlusion and pain score was positive, this technique needs to be refined before use in future studies.

Penetration of sub-micron particles into dentinal tubules using ultrasonic cavitation

OBJECTIVES

Functionalised silica sub-micron particles are being investigated as a method of delivering antimicrobials and remineralisation agents into dentinal tubules. However, their methods of application are not optimised, resulting in shallow penetration and aggregation. The aim of this study is to investigate the impact of cavitation occurring around ultrasonic scalers for enhancing particle penetration into dentinal tubules.

METHODS

Dentine slices were prepared from premolar teeth. Silica sub-micron particles were prepared in water or acetone. Cavitation from an ultrasonic scaler (Satelec P5 Newtron, Acteon, France) was applied to dentine slices immersed inside the sub-micron particle solutions. Samples were imaged with scanning electron microscopy (SEM) to assess tubule occlusion and particle penetration.

RESULTS

Qualitative observations of SEM images showed some tubule occlusion. The particles could penetrate inside the tubules up to 60μm when there was no cavitation and up to ∼180μm when there was cavitation.

CONCLUSIONS

The cavitation bubbles produced from an ultrasonic scaler may be used to deliver sub-micron particles into dentine. This method has the potential to deliver such particles deeper into the dentinal tubules.

CLINICAL SIGNIFICANCE

Cavitation from a clinical ultrasonic scaler may enhance penetration of sub-micron particles into dentinal tubules. This can aid in the development of novel methods for delivering therapeutic clinical materials for hypersensitivity relief and treatment of dentinal caries.

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.