EFFECT OF LOW-LEVEL DIODE LASER ON DENTIN TOPOGRAPHY AND SYMPTOMATIC NONCARIOUS CERVICAL LESIONS PRIOR TO COMPOSITE RESTORATIONS: A SPLIT-MOUTH RANDOMIZED CONTROLLED TRIAL.

OBJECTIVES: This study assessed alterations in sensitivity among symptomatic noncarious cervical lesions (NCCLs) following the application of 3 low-level diode laser wavelengths before composite restoration. It analyzed the changes in dentin topography using a scanning electron microscope (SEM). MATERIALS AND METHODS: Nine patients with 36 NCCLs were randomly assigned intra-individually to 4 groups based on the laser wavelength: laser simulation, 445 nm, 660 nm, and 970 nm. Cavity preparation, irradiation, and composite restoration were performed for each lesion. Sensitivity to cold stimuli was recorded using a visual analog scale (VAS) before the intervention (baseline) and at 1 day, 14 days, 1-, 3-, and 6-month. Pulp sensibility was recorded using an electrical pulp tester (EPT) at baseline, before treatment, and at 3- and 6-month. Additionally, an in vitro examination was performed on 12 extracted human molars to yield 12 dentin discs. Each disc was randomly divided into 4 quadrants to receive the same laser wavelengths to determine the diameters of the tubules using SEM. Results were analyzed statistically for clinical studies by the Friedman test, while ANOVA (RM-ANOVA) was conducted in-vitro, followed by the Bonferroni test in the case of significance (P < .05). RESULTS: VAS readings decreased across all groups, with a significant decrease observed for 660 nm and 970 nm from 14 days to 6-month, while at 445 nm there was a significant decrease at 6-month compared to the control (P < .05). EPT showed a significant decrease in pain threshold levels at 660 nm and 970 nm at 3- and 6-month, while 445 nm showed a significant decrease at 6-month compared to the control (P < .05). The mean tubular diameter at 445 nm decreased, with no significant difference from the control, whereas a significant decrease was found at 660 nm and 970 nm compared to the control (P < .05). CONCLUSIONS: Prior to composite restoration in symptomatic NCCLs, diode lasers with a wavelength of 660 nm showed the highest reduction in sensitivity, followed by 970 nm, whereas 445 nm diode lasers showed the least reduction. Additionally, diode lasers with wavelengths of 660 and 970 nm reduced the width of the dentinal tubules (DT) without inducing melting, as viewed under SEM.

Elemental Sulfur-Mediated Transformation of Carboxylic Acids to Acyl Fluorides by Electrophilic Fluorinating Reagent, Selectfluor.

The elemental sulfur-mediated synthesis of acyl fluorides from carboxylic acids is achieved using Selectfluor. A broad range of acyl fluorides are accessible from carboxylic acids while avoiding the formation of acid anhydrides. 19F NMR spectra suggest that S8-fluoro-sulfonium cation A and neutral S8-difluoride A' generated in situ are the reactive species in this deoxyfluorination reaction.

The effect of sandblasting versus acid etching on the surface roughness and biaxial flexural strength of CAD/CAM resin-matrix ceramics (In vitro study).

BACKGROUND: CAD/CAM resin matrix ceramics are one of the materials used in dental offices. The long-term success of the restoration depends on the bond strength of the restoration to the tooth and other materials; thus, surface treatment of the restoration is necessary to achieve this. But such treatment may affect the restoration strength. The purpose of this study is to assess the impact of various surface treatments on the surface roughness (Ra) and the biaxial flexural strength of two CAD-CAM resin-matrix ceramics. METHODS: Thirty-six-disc-shaped specimens, each measuring 1.2 mm in thickness and 12 mm in diameter, were machined from two resin-matrix ceramic blocks (Lava Ultimate and Cerasmart) (n = 18). Based on the surface treatments, each material was divided into 3 groups: control (no treatment), 50-µm Al2O3 sandblasting, or 9% hydrofluoric acid etching (n = 6). The surface roughness (Ra) was evaluated by the 3D laser scanning microscope. Then, specimens were aged by thermal cycling (5000 cycles) and tested for biaxial flexural strength using a universal testing machine at a crosshead speed of 1.0 mm/min. RESULTS: No significant differences in flexural strength or Ra were found for Lava Ultimate among the surface treatment groups. For Cerasmart, only the sandblasting group showed significantly higher Ra values than the control group. Also, the Ra values for the sandblasting group were significantly higher than those for the acid etching group. The flexural strengths of the sandblasting and acid etching groups for Cerasmart were statistically similar, and both were significantly lower than the control group. CONCLUSIONS: Although all of the applied surface conditioning techniques improved Ra, they had a negative impact on the flexural strength of resin-matrix ceramics. Thus, clinicians should utilize the appropriate surface treatment techniques, taking into account their effects on the surface roughness and mechanical properties of resin-matrix ceramics.

KHMDS/Triglyme Cryptate as an Alternative to Phosphazene Base in Stereodivergent Pentafluoroethylation of N-Sulfinylimines Using HFC-125.

A protocol for the stereodivergent pentafluoroethylation of N-sulfinylimines using HFC-125 with KHMDS/triglyme has been developed. Both diastereomers of the pentafluoroethylated amines can be selectively synthesized based on the presence or absence of triglyme. This additive-controlled protocol allows the KHMDS/triglyme cryptate to be a straightforward and cheap alternative to previously reported base-controlled stereodivergent trifluoromethylation using potassium hexamethyldisilazide (KHMDS) versus P4-tBu.

Tomographic evaluation of direct pulp capping using a novel injectable treated dentin matrix hydrogel: a 2-year randomized controlled clinical trial.

OBJECTIVES: To assess clinically and radiographically the success of pulp capping procedure done in traumatically exposed permanent posterior teeth using a novel injectable treated dentin matrix hydrogel (TDMH), Biodentine, and MTA and to evaluate the formed dentin bridge under the capping materials using CBCT imaging. MATERIALS AND METHODS: 45 patients subjected to accidental traumatic pulp exposures by undergraduate dental students are allocated for this study. For each patient, a pulp capping procedure was done. TDMH was formed of TDM powder and sodium alginate to be injected and then hardened in the defect area. Patients were assigned to 3 groups: TDMH, Biodentine, and MTA, respectively, and returned to the clinic after 3, 6, 12, 18, and 24 months for clinical and radiographic examinations. Tomographic data, including thickness and density of formed dentin bridges, were evaluated at the end of the study period compared to the base line. Pulp sensitivity was evaluated throughout the study period using thermal testing and electric pulp tester. RESULTS: During the follow-up period, all patients were asymptomatic with no clinical signs and symptoms and revealed no radiographic signs of pathosis. However, tomographic evaluation showed the tested materials to have different levels of impact on formed dentin bridges with TDMH group resulted in significantly superior dentin bridges of a higher radiodensity and thickness than Biodentine and MTA. CONCLUSIONS: TDMH has a greater potential to induce dentin bridge formation than Biodentine and MTA under standardized conditions. Additionally, CBCT imaging was confirmed as a non-invasive and inclusive approach to evaluate the formed dentin bridges after pulp capping procedure. CLINICAL RELEVANCE: Direct pulp capping can be done successfully with this novel injectable pulp capping material in future clinical applications. TRIAL REGISTRATION: PACTR201901866476410.

Histological evaluation of the regenerative potential of a novel treated dentin matrix hydrogel in direct pulp capping.

OBJECTIVES: To produce a novel injectable treated dentin matrix hydrogel (TDMH) to be used as a novel pulp-capping agent for dentin regeneration compared with Biodentine and MTA. MATERIALS AND METHODS: Thirty intact fully erupted premolars scheduled to be extracted for orthodontic reasons were included. Pulps were mechanically exposed in the middle of the cavity floor. TDMH was composed of TDM powder (500-µm particle size) and sodium alginate as an injectable scaffold. The capped teeth were divided into three equal groups (n = 10): TDMH, Biodentine, and MTA respectively. Clinical examination and assessment of periapical response were performed. The teeth were extracted after 2-weeks and 2-month intervals, stained with hematoxylin-eosin, and categorized by using a histologic scoring system. Statistical analysis was performed using chi-square and Kruskal-Wallis test (p = 0.05). RESULTS: All teeth were vital during observation periods. Histological analysis after 2 months showed complete dentin bridge formation and absence of inflammatory pulp response with no significant differences between groups. However, the formed dentin was significantly thicker with the TDMH group with layers of well-arranged odontoblasts that were found to form a homogenous tubular structure with numerous dentinal tubule lines showing a positive trend to dentin regeneration. CONCLUSIONS: TDMH could achieve dentin regeneration and conservation of pulp vitality and might serve as a feasible natural substitute for silicate-based cements in restoring in vivo dentin defect in direct pulp-capping procedure. TRIAL REGISTRATION: PACTR201901866476410.