Mid-Infrared Spectroscopy Analysis of the Effects of Erbium, Chromium:Yattrium-Scandium-Gallium-Garnet (Er,Cr:YSGG) Laser Irradiation on Bone Mineral and Organic Components

Comprehensive spectroscopic and morphological analysis of the effects exerted by different acids on Pig bone: Forensic aspect

Demineralization of the chemically treated pig shoulder bone in hydrochloric, hydrofluoric, and acetic acid was monitored by ATR-FTIR, Raman, and LIBS spectroscopies and SEM-EDX technique. SEM-EDX analysis showed reduced calcium and phosphorus content after the treatment with acids and erosion of the overall morphology of the bone compared to the sample kept in water. Alterations in bone structure during the 14-day-long immersion in acid solutions indicated significant chemical changes in the obtained spectra. Fourier deconvolution applied in the amide I (1700-1600 cm-1), phosphate (900-1200 cm-1), and carbonate (500-650 cm-1) region indicated the presence of different components in the bone sample, depending on the environment and acid concentration, providing information about the composition. Parameters such as mineral-to-matrix ratio, crystallinity index, and carbonate-to-phosphate ratio were calculated and compared using ATR-FTIR and Raman data. These parameters were also correlated with calcium ionic-to-atomic and phosphorous-to-carbon line intensities obtained from LIBS spectra. Calcium and phosphorus atomic contents obtained by SEM-EDX analysis were in agreement with LIBS data. The results suggested that an increase in acid concentration has primarily affected the phosphate band's intensity and structure, as the phosphate content was more susceptible to demineralization. Hydrochloric acid was proven to be a more powerful demineralization agent than hydrofluoric and acetic acids. The results of this study could be further applied to the investigation of the bone remains at the crime scene, especially when their removal is attempted by immersion in acid solutions.

Impact of Type 2 Diabetes Mellitus on the Occurrence of Vertical Root Fracture: A Case Control Study

INTRODUCTION

The aim of this case-control study was to examine the relationship between type 2 diabetes mellitus (DM) and the occurrence of VRFs. The crack extension, dentin sclerosis, and chemical characteristics of root dentin in teeth with VRF from patients with/without DM were also compared.

METHODS

One hundred and thirty-two patients diagnosed with VRF in crowned root filled posterior teeth were selected. The study was conducted in 2 parts. In Part-1: The cases were matched with control teeth (1:1) for age (±5 years), sex, tooth type, apical extent of root filling, time period after root filling to a diagnosis of VRF, presence or absence of intracanal post and abutment status. The presence or absence of type 2 DM (HbA1c > 6.5) was recorded. In Part-2: The extracted teeth with VRF from the case control study were used to evaluate the extension of VRF, presence of sclerotic dentin and isthmus using a microscopic analysis; while the levels of pentosidine, collagen cross-linking ratio and mineral-collagen ratio were determined by Fourier-transform infrared spectroscopy. The distribution of DM between cases and controls was analyzed using Pearson Chi-Square test and Odds Ratio estimated. Chemical composition data was analyzed using Mann-Whitney test. The extent of sclerotic dentin was analyzed using Pearson Chi-Square test.

RESULTS

When compared to patients without DM, patients with DM had 2.67 (95% CI: 1.6-4.45) folds higher odds for occurrence of VRF. Pentosidine (P = .014), collagen cross-linking ratio(P = .047), mineral-collagen ratio (P = .009) and sclerotic dentin extent (P = .0009) were significantly higher in patients with DM and VRF.

CONCLUSIONS

Type 2 DM was more often associated with VRFs in root canal treated teeth with crowns. Root dentin from patients with type 2 DM and VRF had higher levels of pentosidine, collagen cross-linking ratio, mineral to collagen ratio and sclerotic dentin.

Efficient continuous wave and passively Q switched Er:GdScO3 laser using Fe:ZnSe at 2.8 µm

We report on diode-pumped continuous wave and passively Q switched Er:GdScO₃ crystal lasers at around 2.8 µm. A continuous wave output power of 579 mW was obtained with a slope efficiency of 16.6%. Using Fe:ZnSe as a saturable absorber, a passively Q switched laser operation was realized. A maximum output power of 32 mW was generated with the shortest pulse duration of 286 ns at a repetition rate of 157.3 kHz, leading to a pulse energy of 204 nJ and a pulse peak power of 0.7 W.

Effects of Er, Cr: YSGG Laser on Shear Bond Strength of the Orthodontic Brackets for 5 and 10 Seconds: An In Vitro Study

Objectives. The study designed to compare the effect of erbium, chromium: yttrium-scandium-gallium-garnet (Er, Cr: YSGG) laser at different power outputs and short periods of time (5 and 10 s) and acid etching on the shear bond strength (SBS) and failure mode of metallic orthodontic brackets. Material and methods. A total of sixty-nine human premolars extracted for orthodontic purposes were used. 60 teeth were randomly assigned to one of the five treatment groups. (n = 12): group 1: 37% phosphoric acid etching and groups 2–5: the enamel surface irradiated by the Er, Cr: YSGG laser operated at different power outputs (1 W, 1.5 W, 2 W, and 2.5 W), each laser group was divided into two subgroups (n = 6) according to exposure time (5 s and 10 s). Nine teeth were not subjected to SBS testing but were prepared for scanning electron microscopy (SEM). The nonparametric Kruskal–Wallis test was used to evaluate the data; the SBS and adhesive remanent index (ADI) were evaluated. Results. The mean SBS for all laser groups and the acid-etched group were comparable, with no significant differences except for the 1 W group for 5 and 10 s and the 1.5 W group for 5 s. For the ARI scores, no statistically significant difference was found among the groups ( $P=0.059$ ), and the majority of the samples had ARI type 2 or 3. Conclusion. The laser irradiation at 2 and 2.5 W for 5 s was similar to that produced by acid etching, whereas the laser irradiation at 2 and 2.5 W at 10 s was higher compared with that obtained with acid etching and adequate to etch the enamel.

Morphological, optical, and elemental analysis of dental enamel after debonding laminate veneer with Er,Cr:YSGG laser: A pilot study

Laminate veneer removal is becoming a routine procedure at the dental clinic and the use of laser can facilitate its removal. This work aimed to evaluate the morphological, elemental, and optical changes in the remaining enamel after veneer removal using Er,Cr:YSGG laser. Forty-four enamel slabs were prepared and randomly distributed into nine experimental groups, for bonding using lithium disilicate laminates with three different luting agents (Variolink Veneer, RelyX U200, and RelyX Veneer). Then each agent was debonded using Er,Cr:YSGG laser (2.78 μm) using two different protocols:3.5 W, 48.14 J/cm² , 20 Hz non-contact and 3.0 W, 48.14 J/cm² , 20 Hz non-contact. The morphological, optical, and elemental analysis of enamel was performed before cementation and after laser debonding, using scanning electron microscopy (SEM), optical coherence tomography (OCT), and energy-dispersive X-ray spectroscopy (EDS). The level of statistical significance adopted was 5%. The EDS analysis of enamel after debonding revealed a significant increase in silane and carbon, as well as a decrease in calcium and phosphate contents. Analysis showed the presence of residual cement in most experimental groups but the morphological analysis showed alteration of the enamel's prisms only in the groups that used RelyX Veneer and Variolink Veneer cements. There was no evidence of deleterious morphological changes resulting from irradiation. However, an increase in the optical attenuation coefficient by the OCT was observed due to the presence of the remaining cement. It can be concluded that the Er,Cr:YSGG laser, in the mean powers used, is efficient for veneer removal without causing deleterious effects for the enamel.

Influence of hyperbaric oxygen on biomechanics and structural bone matrix in type 1 diabetes mellitus rats

Background

The aim of this study was to evaluate the biomechanics and structural bone matrix in diabetic rats subjected to hyperbaric oxygen therapy (HBO).

Methods

Twenty-four male rats were divided into the following groups: Control; Control + HBO; Diabetic, and Diabetic + HBO. Diabetes was induced with streptozotocin (STZ) in the diabetic Groups. After 30 days, HBO was performed every 48h in HBO groups and all animals were euthanized 60 days after diabetic induction. The femur was submitted to a biomechanical (maximum strength, energy-to-failure and stiffness) and Attenuated Total Reflectance Fourier transform infrared (ATR-FTIR) analyses (crosslink ratio, crystallinity index, matrix-to-mineral ratio: Amide I + II/Hydroxyapatite (M:MI) and Amide III + Collagen/HA (M:MIII)).

Results

In biomechanical analysis, diabetic animals showed lower values of maximum strength, energy and stiffness than non-diabetic animals. However, structural strength and stiffness were increased in groups with HBO compared with non-HBO. ATR-FTIR analysis showed decreased collagen maturity in the ratio of crosslink peaks in diabetic compared with the other groups. The bone from the diabetic groups showed decreased crystallinity compared with non-diabetic groups. M:MI showed no statistical difference between groups. However, M:MIII showed an increased matrix mineral ratio in diabetic+HBO and control+HBO compared with control and diabetic groups. Correlations between mechanical and ATR-FTIR analyses showed significant positive correlation between collagen maturity and stiffness.

Conclusions

Diabetes decreased collagen maturation and the mineral deposition process, thus reducing biomechanical properties. Moreover, the study showed that HBO improved crosslink maturation and increased maximum strength and stiffness in the femur of T1DM animals.