Effect of Diabetes on Tubular Density and Push-out Bond Strength of Mineral Trioxide Aggregate to Dentin

Effects of Diabetes on Elemental Levels and Nanostructure of Root Canal Dentin

INTRODUCTION

This study evaluated the effects of diabetes mellitus (DM) on the nanostructure of root canal dentin using high-resolution transmission electron microscopy (HRTEM) and inductively coupled plasma mass spectrometry (ICP-MS).

METHODS

Twenty extracted human premolars from diabetic and nondiabetic patients (n = 10 in each group) were decoronated and sectioned horizontally into 40 2-mm-thick dentin discs, with each disc designated for a specific test. ICP-MS was used to determine the different elemental levels of copper, lithium, zinc, selenium, strontium, manganese, and magnesium in diabetic and nondiabetic specimens. HRTEM was used to analyze the shape and quantity of the apatite crystals in diabetic and nondiabetic dentin at the nanostructural level. Statistical analysis was performed using Kolmogorov-Smirnov and Student t test (P < .05).

RESULTS

ICP-MS revealed significant differences in trace element concentrations between the diabetic and nondiabetic specimens (P < .05), with lower levels of magnesium, zinc, strontium, lithium, manganese, and selenium (P < .05), and higher levels of copper in diabetic specimens (P < .05). HRTEM revealed that diabetic dentin exhibited a less compact structure with smaller crystallites and significantly more crystals in the 2500 nm2 area (P < .05).

CONCLUSION

Diabetic dentin exhibited smaller crystallites and altered elemental levels more than nondiabetic dentin, which could explain the higher root canal treatment failure rate in diabetic patients.

Current status and future prospects of stomatology research

Research in stomatology (dental medicine) continues to expand globally and is oriented towards solving clinical issues, focusing on clarifying the clinical relevance and potential mechanisms of oral‍-‍systemic connections via clinical epidemiology, oral microecological characterization, and the establishment of animal models. Interdisciplinary integration of materials science and tissue engineering with stomatology is expected to lead to the creation of innovative materials and technologies to better resolve the most prevalent and challenging clinical issues such as peri-implantitis, soft and hard tissue defects, and dentin hypersensitivity. With the rapid development of artificial intelligence (AI), 5th generation mobile communication technology (5G), and big data applications, "intelligent stomatology" is emerging to build models for better clinical diagnosis and management, accelerate the reform of education, and support the growth and advancement of scientific research. Here, we summarized the current research status, and listed the future prospects and limitations of these three aspects, aiming to provide a basis for more accurate etiological exploration, novel treatment methods, and abundant big data analysis in stomatology to promote the translation of research achievements into practical applications for both clinicians and the public.

Neural network approach to evaluate the physical properties of dentin

This study intended to evaluate the effects of inorganic trace elements such as magnesium (Mg), strontium (Sr), and zinc (Zn) on root canal dentin using an Artificial Neural Network (ANN). The authors obtained three hundred extracted human premolars from type II diabetic individuals and divided them into three groups according to the solutions used (Mg, Sr, or Zn). The authors subdivided the specimens for each experimental group into five subgroups according to the duration for which the authors soaked the teeth in the solution: 0 (control group), 1, 2, 5, and 10 min (n = 20). The authors then tested the specimens for root fracture resistance (RFR), surface microhardness (SμH), and tubular density (TD). The authors used the data obtained from half of the specimens in each subgroup (10 specimens) for the training of ANN. The authors then used the trained ANN to evaluate the remaining data. The authors analyzed the data by Kolmogorov-Smirnov, one-way ANOVA, post hoc Tukey, and linear regression analysis (P < 0.05). Treatment with Mg, Sr, and Zn significantly increased the values of RFR and SμH (P < 0.05), and decreased the values of TD in dentin specimens (P < 0.05). The authors did not notice any significant differences between evaluations by manual or ANN methods (P > 0.05). The authors concluded that Mg, Sr, and Zn may improve the RFR and SμH, and decrease the TD of root canal dentin in diabetic individuals. ANN may be used as a reliable method to evaluate the physical properties of dentin.

Type 2 diabetes and the clinically normal pulp - An in-vitro study

Aim

The aim of this study was to investigate the effect of type 2 diabetes (T2D) on clinically normal dental pulp tissue by using special stains and immunohistochemistry (IHC) to determine the morphology of the coronal pulp and distribution of immune markers in non‐T2D and T2D groups.

Methodology

Ethics approval for this in vitro pilot study was obtained from the University of Otago Human Ethics Committee (16/069). Twenty extracted permanent molar teeth diagnosed as having clinically normal pulp status were collected. Ten teeth were from participants with well‐controlled T2D and ten from participants without diabetes (non‐T2D). Each tooth was sectioned transversely at the cemento‐enamel junction before the crowns were decalcified and embedded in paraffin. Sections were stained with haematoxylin and eosin, Massons trichrome, and van Gieson stains for histological and morphological evaluation. IHC using anti‐CD4, anti‐CD68 and anti‐CD83 and anti‐IL1β, anti‐IL6, anti‐IL17, anti‐TNF‐α, anti‐TLR2, anti‐TLR4 and anti‐FOXP3 identified proteins of interest. Qualitative and semi‐quantitative analyses evaluated the morphology of the dental pulp and protein expression. Data analyses were performed with GraphPad Prism, using Student's t‐test and multiple regression using SPSS at p < .05.

Results

Special stains demonstrated morphological differences in the T2D dental pulp compared with non‐T2D. Qualitative analysis indicated that the pulp in the T2D samples was consistently less cellular, less vascular, showed evidence of thickened blood vessel walls, increased pulp calcification and collagen deposition. Semi‐quantitative analysis of IHC samples showed the T2D pulp had significantly increased expression of macrophage and dendritic cell markers CD68 (p < .001) and CD83 (p = .04), and there was significantly greater expression of inflammatory cytokines IL1β (p = .01), IL6 (p < .0001), IL17 (p < .0001) and TNF‐α (p = .01). T2D samples showed a significant increase in markers of innate inflammation, TLR2 (p < .001) and TLR4 (p < .001) and decreased expression of regulatory T‐cell marker, FOXP3 (p = .01). Multiple regression showed that age‐corrected differences were statistically significant.

Conclusion

Preliminary findings suggest that T2D may exert a similar response in the pulp to complications in other body sites. Hyperglycaemia is associated with changes in the morphology of the clinically normal dental pulp with altered immune cell and cytokine expression.

The effect of diabetes on the tensile bond strength of a restorative dental composite to dentin

This study was performed to evaluate the effect of diabetes mellitus (DM) on the tensile bond strength (TBS) of dental composite resin bonding to enamel and dentin of extracted human teeth. Thirty caries-free human premolar teeth (10 from type 1 DM (D1), 10 from type 2 DM (D2), and 10 from non-diabetic individuals (control)) were wet ground and polished to obtain flat surfaces of dentin (n = 10). 37% phosphoric acid was used to etch dentin specimens for 15 s. After the application of the adhesive system, the composite resins were applied and cured for 20 s. Then, specimens were subjected to TBS testing by Universal Testing Machine (1 mm/min). One specimen from each group was prepared and observed under a scanning electron microscope (SEM) and a dot map was generated. Data were analyzed by ANOVA and post hoc Tukey tests (α = 0.05). The TBS values were significantly higher in the control group compared to the D1 and D2 groups (P < 0.05). Between DM groups, D2 values were significantly higher than those in the D1 group. Unlike DM groups, the zigzag fracture pattern was only noticed in the control group. DM adversely affected the TBS of dental composite resins to dentin; this negative effect is more exaggerated by type 1 DM than type 2 DM.

The effect of diabetes mellitus on the shear bond strength of composite resin to dentin and enamel

Diabetes mellitus might be linked to the deterioration of certain physical properties of dentin and enamel. This study aimed to determine the effect of two types of diabetes on the shear bond strength of enamel and dentin, by using the single bond universal bonding system. Sixty specimens [from 15 teeth; 5 from each group-non-diabetic (ND), Diabetic type I (D1), and Diabetic type II (D2)], were prepared with equal amounts of dentin (n = 5) and enamel (n = 5). Enamel specimens (E20) were etched with 37% phosphoric acid, for 20 s, and dentin specimens (D15) were etched for 15 s. A standard shear bond strength test was performed on all specimens. Their failure modes were also studied under a scanning electron microscope, and the data were analyzed by using ANOVA and Post Hoc Tukey's test (a = 0.050). For the enamel groups, significant differences were only noticed between the ND and D1 (P < 0.050) groups, and between the ND and D2 (P < 0.050) groups. In the dentin groups, there was a significant difference only between the ND and D1 (P < 0.050) groups. The micrographs showed that the ND group had the highest number of specimens with cohesive failure and D1 had the highest number of specimens with adhesive failure. It can be concluded that both types of diabetes reduce the shear bond strength of composite resin on dentin and enamel. However, it seems that the negative effect of diabetes on shear bond strength of dental composite resin is more drastic in individuals with type I diabetes as compared with type II.

The effect of diabetes on Fracture Resistance of Teeth: An in vitro study

The root fracture resistance (RFR) of premolars extracted from diabetic patients and the effect of biomaterials: white mineral trioxide aggregate (WMTA) and WMTA+Na₂ HPO₄ as an additive, on enhancing RFR were evaluated. Diabetic and non-diabetic teeth were divided into 4 subgroups (n = 5): root canals were obturated with WMTA, WMTA+Na₂ HPO₄ , gutta-percha and one unfilled (control). A plunger (1 mm diameter) applied a downward compressive load with crosshead speed of 1 mm min^-1 on the specimens mounted on resin blocks, and the ultimate force to fracture was measured. The mean RFR values of diabetic specimens were significantly lower. The lowest and highest means of RFR were recorded in the control and WMTA, in normal group and the control and WMTA+Na₂ HPO₄ in the diabetic group, respectively. The RFR in diabetic patients was significantly lower, indicating their higher susceptibility to fracture under vertical forces. The use of WMTA (with or without Na₂ HPO₄ ) for obturation enhances the RFR.