Evaluation of the effectiveness of micro-Raman spectroscopy in monitoring the mineral contents change of human enamel in vitro.

The purpose of this in vitro study was to investigate the efficacy of micro-Raman spectroscopy on detecting mineral content change during the demineralization and de/remineralization cycling process. The enamel samples (n = 55) were randomly divided into three groups and separately treated with demineralization solution (n = 20), de/remineralization cycling solution (n = 30), and distilled water (n = 5). Micro-Raman spectroscopy, microhardness (MHS), and the released calcium ions concentration were performed before and after treatment, respectively. A one-way analysis of variance (ANOVA) with a post hoc Tukey test was used to analyze the results. The Spearman correlation coefficients among the parameters of Raman relative intensity decrease (RRID%), the percentage of MHS loss (PML), and the released calcium ions concentration were also analyzed. In demineralization group, RRID%, PML, and released calcium ions concentration were highly correlated with each other (r = 0.979, p < 0.001; r = 0.984, p < 0.001; and r = 0.983, p < 0.001, respectively). While for the de/remineralization cycling group, there also existed a high correlation between RRID% and PML (r = 0.987, p < 0.001). In conclusion, micro-Raman spectroscopy could effectively monitor the mineral content change, and its efficacy was validated by the measurement of released calcium ions concentration and MHS.

Imaging analysis of 1 138 supernumerary teeth by using cone-beam computed tomography.

OBJECTIVES: This study aims to analyze and summarize the characteristics of supernumerary teeth by using cone-beam computed tomography (CBCT). METHODS: A total of 718 patients with 1 138 supernumerary teeth were retrospectively collected. Age, gender, number, location, morphology, eruption status, and accompanying symptoms of the supernumerary teeth were statistically analyzed. The relationship relative to jaws, gender, and eruption status were analyzed and discussed. RESULTS: The average age of the patients was 9.54±5.32 years, and the male to female ratio was 2.88∶1. About 77.02% of the patients sought medical advice during the mixed dentition period, and 50.70% had one supernumerary tooth. These supernumeraries were most commonly conical in shape, and 85.76% of them were in the incisor region, 92.09% in the upper jaw, 46.75% in inverted position, and 86.20% unerupted. Overall, 65.29% of them had fully developed roots, and 60.63% had an impact on adjacent structures. Significant differences were found in eruption status, morphology, zoning, direction, root development, and impact on adjacent structures between the supernumerary teeth located in the upper and lower jaws (P<0.05). Significant differences were also detected in gender, morphology, zoning, orientation, root development, and impact on adjacent structures between erupted and unerupted teeth (P<0.05). The incidence of supernumerary teeth in the incisor region was higher in males than that in females. Moreover, the root of supernumeraries was more completely developed in males than in females (P<0.05). CONCLUSIONS: For supernumerary teeth, CBCT images can provide accurate three-dimensional radiographic data and are valuable for clinical diagnosis and treatment planning.

Comparison of surgical effects between the modified West China method and Millard method in repairing unila-teral cleft lip.

OBJECTIVES: The purpose of this study is to compare the surgical effects of the modified West China method and Millard methods for repairing unilateral cleft lip. METHODS: A total of 34 cases of unilateral cleft lip were analyzed, composed of 16 cases in the experimental group subjected to the modified West China method and 18 cases in the control group, which was subjected to the Millard method. Photographs before and after operation were compared, and SPSS 21.0 was used in statistical analysis. RESULTS: After operation, no significant difference in symmetry between the healthy and affected sides of the nasal alar foot (sba), nasal alar point (al), lip peak point (cph), and mouth angle point (ch) in the experimental group (P>0.05), but no significant difference in symmetry was found between healthy and affected sides of cph and ch in the control group (P>0.05). No significant differences in the symmetry rates of the sba, cph, ch and the nasal columella regression rates were found between the experimental and control groups (P>0.05). The symmetry rates of the al in the experimental group were higher (P<0.05). CONCLUSIONS: For unilateral cleft lip repair, two methods had better effects on lip repair, but the nasal symmetry showed greater improvement when the modified West China me-thod was used than when the Millard method was used.

[A finite element study of the influence of upper lip pressure on the development of maxilla after cleft lip surgery].

PURPOSE: To explore the mechanism of upper lip pressure on maxilla after cleft lip surgery. METHODS: ANSYS 17.0 software was used to add the upper lip soft tissue to the finite element model of maxilla with cleft palate, and the material properties was assigned to form a three-dimensional finite element model of maxilla with upper lip. The upper lip pressure was applied to the model and force analysis was performed in 2 groups. In the experimental group, upper lip pressure with cleft lip surgery was applied; in the control group, upper lip pressure in normal children of the same age was applied. RESULTS: Maxillary deformation in the experimental group was greater than that in the control group. Maxillary deformation occurred in three-dimensional direction, which was mainly in Z axis, followed by X axis and Y axis. The anterior segment of alveolar process was the most obvious，and from the anterior to the posterior, the change trend was gradually decreased. CONCLUSIONS: Maxillary growth is inhibited in three-dimensional direction,which is mainly sagittal growth inhibition,followed by transverse and vertical growth. The inhibition gradually decreases from anterior to posterior.

Effects of different concentrations and exposure time of sodium hypochlorite on the structural, compositional and mechanical properties of human dentin.

This study evaluated the effects of sodium hypochlorite (NaOCl) with different concentrations and exposure time on the structural, compositional and mechanical properties of human dentin in vitro. Sixty dentin slabs were obtained from freshly extracted premolars, randomly distributed into four groups (n=15), and treated with 1%, 5%, 10% NaOCl and distilled water (control group), respectively, for a total of 60 min. Attenuated total reflection infrared (ATR-IR) spectroscopy, Raman spectroscopy and X-ray diffraction (XRD) were carried out before, 10 min and 60 min after the treatment. Scanning electron microscopy (SEM) and flexural strength test were conducted as well. The results showed that dentins experienced morphological alterations in the NaOCl groups, but not in the control group. Two-way repeated-measures analysis of variance revealed that the carbonate:mineral ratio (C:M), Raman relative intensity (RRI), a-axis, c-axis length and full width at half maximum (FWHM) with the increase of time and concentration in the NaOCl groups were not significantly different from those in the control group (P>0.05). Nevertheless, the mineral:matrix ratio (M:M) increased and the flexural strength declined with the increase of concentration and the extension of time in the NaOCl groups (P<0.05). Additionally, it was found that the M:M and the flexural strength remained unchanged after 1% NaOCl treatment (P>0.05), and the morphology changes were unnoticeable within 10 min in 1% NaOCl group. These results indicated that NaOCl has no significant effects on the inorganic mineral of human dentin; but it undermines and eliminates the organic content concentration- and time-dependently, which in turn influences the flexural strength and toughness of dentins. In addition, an irrigation of 1% NaOCl within 10 min can minimize the effects of NaOCl on the structural and mechanical properties of dentin during root canal treatment.