Effects of desensitizing dentifrices on dentin tubule occlusion and resistance to erosive challenges

Background Many studies have demonstrated efficacy of casein phosphopeptide (CPP) containing products for dentin tubule occlusion for treatment of dentin sensitivity, but their effectiveness under dynamic erosive challenges remains to be elucidated. The purpose of the present study was to investigate the effectiveness of a desensitizing dentifrice containing CPP in occluding dentin tubules and resisting erosive challenges in comparison to that containing polyvinyl methyl ether/maleic acid (PVM/MA) copolymers. Methods A total of 33 dentin discs were prepared from coronal sections of human third molars and divided into 3 groups: a toothpaste containing CPP; a toothpaste containing PVM/MA and submicron silica; and a regular toothpaste (Controls). A soft-bristle toothbrush was used to brush the dentin discs with the dentifrices for 45 strokes in 30 s at a force of approximately 200 g. The brushing cycle was repeated after immersion of the dentin discs in artificial saliva overnight. The dentin discs were then challenged in orange juice for 10 min in an incubator rocking at 120 rpm. Three fields were randomly selected on each dentin disk surface to assess dentin tubule occlusions after each brushing cycle and after orange juice challenge with a 3D laser scanning microscope. Specimen cross sections were examined with a scanning electron microscope equipped with energy dispersive spectroscopy (SEM/EDS). Results After the first and second cycles of brushing, dentin tubules were occluded on average by 56.3% and 85.7% in CPP group, 66.2% and 88.1% in PVM/MA group, and 0.0 and 13.0% in the controls, respectively. There were no statistically significant differences in dentin tubule occlusions between the CPP and PVM/MA groups after two cycles of brushing (p>0.05). After dynamic erosive challenges with orange juice, 20.3% of the dentin tubules in the CPP group, 79.1% in the PVM/MA group and none in the control remained occluded (P<0.05). SEM/EDS imaging showed that dentin tubules were blocked with plugs containing dentifrice substances in CPP and PVM/MA groups after treatments, but none in the controls. Conclusions Desensitizing dentifrices containing CPP or PVM/MA could effectively occlude dentin tubules after two cycles of brushing. PVM/MA in combination with submicron silicon dioxide exhibited stronger resistance to dynamic erosive challenges by acidic beverages. Inorganic fillers that can enter dentin tubules and resist erosive challenges may be key for desensitizing dentifrices.

Surface Characterisation of PEEK and Dentin, Treated with Atmospheric Non-Thermal PDD Plasma, Applicable for Dental Chair-Side Procedures

This study investigates the suitability of Piezoelectric Direct Discharge Plasma as a tool for wetting behaviour modification of PEEK and dentin, and compares the results of this method with low-pressure plasma treatment and phosphoric acid etching. Static contact angle measurements were made, roughness was assessed using tactile measurement, and AFM and SEM images were taken. An optimum operating distance of ≤15 mm was determined for the plasma based on the water contact angle. Furthermore, it was demonstrated that despite only a fraction of the power, the PDD plasma also produces hydrophilic and nanostructured PEEK surfaces with a 38° water contact angle in the same plasma time. In contrast, the gold standard of dental surface modification of dentin—phosphoric acid etching—showed no measurable contact angle due to the exposed dentin tubules. Treatment with PDD plasma reduces the water contact angle of dentin from 65° to 43° and is not negative affected by water. Wet, PDD plasma-treated dentin samples show a water contact angle of only 26.5°. The dentin tubules exposed by chemical etching led to a significantly increased roughness. No comparable effect could be demonstrated for plasma treatment on dentin, but based on the contact angle measurements, a chemically strongly activated surface with strongly polar interaction behaviour can be assumed. The additional use of the PDD plasma technique to improve wetting could therefore have a positive effect on the adhesive bond between human dentin and polymeric dental restorative materials or, depending on the adhesive system, replace the etching process altogether.

Effect of high-power diode laser on radical surfaces exposed as dental tubules obliteration: in vitro study

The aim of this study was to find adequate parameters of high-power diode laser for obliteration of dental tubules. Newly extracted human teeth (molars) were used for the research that were treated with high-power diode laser and then evaluated by scanning electron microscopy. Roots of 10 healthy teeth were used and prepared in 40 dentin blocks and dividing them into 4 groups: Control Group; G1, G2, G3 (groups treated with high-power diode laser), varying power, energy and application time. The images were evaluated randomly by 2 blinded, calibrated examiners who attributed scores to each image with a level of significance of 5%. The null hypothesis there was no difference between the groups tested regarding of the obliteration of the dentinal tubules. Considering the scores used for analyzing the SEM images, statistically significant differences were observed between the control and all the experimental groups (p < 0,05). However, the irradiated (experimental) groups showed no statistically significant differences between them, because at all the tested parameters the dentin tubules were shown to be obliterated (p < 0.05). The efficacy can be completed in the obliteration of tubules and interruption of fluid movement within the dentin tubules with treatment of the exposed surface with the high-power diode laser; however, the parameters of power and energy lowest showed better results.

Assessment of the acid resistance behaviour of dentin tubules occluded by different desensitizers

Aim: To evaluate the efficacy of in-office and home-based products in the prevention of dentinal hypersensitivity on dentin discs. Methodology: Ninety-six dentin disc samples of 1 mm were divided equally into six groups as follows: TeethmateTM, Smartprotect®, novamin®, Arginine calcium carbonate, potassium oxalate with rinse and saline (control). After acid etching, test agents were applied, and eight samples in each group were subjected to citric acid. SEM examination (3000x) and statistical analysis were carried out. Results: Before citric acid challenge, novamin® and teethmate had superiority when compared to others (p<0.001), but there was no a statistical difference between novamin® and teethmate. After citric acid challenge, teethmate and smartprotect showed resistance on occluded tubules. The decreasing in the level of occluded tubules in novamin® group was statistically significant (p<0.05). In-office products including teethmate and smartprotect were found more successful compared to home-based products. Smartprotect resisted against to citric acid (0.506). Conclusion: Novamin® showed a successful occlusion in all tubules before acid challenge whereas; it was the most unsuccessful group after acid challenge when compared to other agents. In-office agents were found to be more successful in reducing dentine permeability than home-care products. In-office agents showed more resistance to acid attacks. Further studies are needed to assess the efficacy of desensitizer agents. How to cite this article: Karayürek F, Arpağ OF. Assessment of the acid resistance behaviour of dentin tubules occluded by different desensitizers. Int Dent Res 2020;10(3):80-9. https://doi.org/10.5577/intdentres.2020.vol10.no3.3 Linguistic Revision: The English in this manuscript has been checked by at least two professional editors, both native speakers of English.

Immunohistochemical study of dental pulp cells with 3D collagen type I gel in demineralized dentin tubules in vivo

Dental pulp cells (DPCs) represent good candidates for the regeneration of dental tissue. This study aimed to evaluate the growth and differentiation potential of DPCs cultured inside demineralized dentin tubules in vivo. Six green fluorescent protein (GFP)-transgenic rats (body weight 100 g each) and thirty-two Sprague-Dawley (SD) male rats (body weight 250 g each) were used for DPC collection and dentin tubules preparation and transplantation, respectively. Third-passage DPCs with or without collagen gels were loaded into demineralized dentin tubules. Both types of grafts were transplanted into the rectus abdominis muscles of SD rats and were harvested after 21 days. The expression of alkaline phosphatase (ALP), bone sialoprotein (BSP), osteopontin (OPN), nestin, and dentin sialoprotein (DSP) were analyzed by immunohistochemistry. Histological analysis showed that DPCs in the collagen gel formed an osteodentin-like hard tissue matrix after 21 days. Increased positive immunoreactivity for ALP, BSP, OPN, nestin, and DSP was observed in experimental groups compared with control. Our results demonstrate that DPCs in collagen gel inside demineralized dentin tubules show increased growth and differentiation.