A Comparison of the Clinical Axial Extension of Class II Carious Lesions with Different Diagnostic Images

[null]Master of ScienceRestorative DentistryUniversity of Michiganhttp://deepblue.lib.umich.edu/bitstream/2027.42/91025/1/Bin-Shuwaish_Mohammed_SH-THESIS-FINAL.pd

Compliance of dental laboratory technicians with dentists’ instructions for fabrication of a PFM crown

Objectives: The aim of this study was to evaluate the compliance of dental technicians from different dental laboratories with dentists’ written prescriptions during fabrication of porcelain-fused-to-metal (PFM) crowns. Materials & methods: Final impressions for a prepared Ivorine tooth no. 21 were sent to 16 dental laboratories (8 government and 8 commercial) for fabrication of a PFM crown. A detailed, standard work authorization form accompanied each case, including a request to fabricate a uniform-thickness metal framework, with incisal translucency, hypocalcification-like stain, porcelain facial shoulder and metal palatal chamfer margins with palatal occlusion in porcelain. All crowns were then collected, and data were recorded and analyzed statistically with Fisher’s Exact and Pearson’s Chi-square tests by means of SPSS and WinPepi software. Results: No statistically significant differences were found between laboratory groups in following the instructions for metal substructure thickness (P > 0.6), facial and palatal margins (P = 1.0) or the dimensions of the hypocalcification-like stain (P = 0.28). However, commercial labs were significantly better than government labs in the location criteria for hypocalcification and incisal translucency (P = 0.04). When the total numbers of successfully followed criteria were compared, commercial labs were found to be significantly better than government labs in following the written instructions (P = 0.002). Conclusion: Although a standard work authorization form was used, commercial labs performed better than government labs, especially in esthetic characterizations such as hypocalcification-like staining and incisal translucency

Influence of graphene oxide filler content on the dentin bond integrity, degree of conversion and bond strength of experimental adhesive. A SEM, micro-Raman, FTIR and microtensile study

The study aimed to evaluate the effect of graphene oxide (GO) nano-filler content in experimental dental adhesive on its degree of conversion (DC), microtensile bond strength ( μ TBS) and structural reliability, using Fourier transform infrared spectroscopy (FTIR), Micro-Raman spectroscopy and Scanning electron microscopy (SEM). A resin adhesive was fabricated (control adhesive - CA) and fabricated GO nano-particles were added at 0.5% and 2.0% (m/m) to produce adhesives GOA1 and GOA2 respectively. One hundred and two teeth (specimens) were prepared for dentin exposure and conditioned with 36% phosphoric acid. Specimens in each group (n = 34) were treated with formulated adhesives (CA, GOA1 & GOA2) and photo-polymerized for 20 s followed by composite build up. Sixty specimens were used for μ TBS testing in the adhesive groups (CA, GOA1 & GOA2), with half exposed to thermocycling (TC) whereas the remaining half (n = 10) stored in distilled water. Seven specimens each were assessed using SEM and Micro-Raman spectroscopy, in each adhesive group (n = 7). DC for the adhesives was assessed using FTIR. The means of μ TBS and DC were analyzed using ANOVA and post hoc Tukey multiple comparisons test. GO nano-filler content showed significant influence on the adhesive μ TBS in comparison to controls (p  0.05). DC was significantly higher in control adhesive [46.8 (3.6)%] compared to GOA2 [37.7 (4.2)%] specimens, however DC was comparable among GOA1 [42.3 (2.9)%] and GOA2 [37.7 (4.2)%] specimens (p > 0.05) respectively. GO exhibited interaction within adhesive and tooth dentin comparable to control adhesive. Increasing GO content showed increase in μ TBS of adhesive to dentin, but a decrease in degree of conversion. Under ideal conditions, experimental adhesive with 2% GO content showed acceptable bond strength and DC; and should be further assessed under dynamic conditions to recommend clinical use

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-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) was 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