ABSTRACT
OBJECTIVE: Carious tissue discrimination in clinical operative caries management relies traditionally on the subjective hardness of carious dentine. Biochemical alterations within the lesion have the potential to discriminate the lesion zones objectively. This study aimed to determine the correlation between the biochemical proportions of amide I and phosphate moieties as these are the most prominent peaks found in dentine with the Knoop microhardness of carious dentine zones, using non-contact Raman spectroscopy. The null hypothesis investigated was that there was no correlation between Raman peak ratios, amide I: phosphateν1, and the Knoop microhardness within specific zones of a carious lesion. METHODS: 423 scan points from 20 carious dentine lesion samples examined using high-resolution Raman spectroscopy. The peak ratio of the characteristic vibration mode of amide I (1650 cm-1) and phosphate (960 cm-1) bands were calculated, following a straight line path through the lesion to the pulp and correlated to corresponding Knoop microhardness measurements. RESULTS: Using logistic regression analysis, clear correlations were found between the Knoop microhardness and Raman peak ratio cut-off values between caries-infected and caries-affected dentine (81.5 % sensitivity / 92.7 % specificity), with a lower specificity (2.7 %) found between caries-affected and sound dentine. CONCLUSION: This study concluded that non-contact Raman spectroscopy can be used in vitro to discriminate objectively between the different zones of a carious dentine lesion at high resolution, using the Raman peak ratios, amide I : phosphate ν1. CLINICAL SIGNIFICANCE: Specific biochemical alterations have the potential to be used in-vitro and in-vivo to identify the end-point of selective carious lesion excavation.
Subject(s)
Dental Caries , Dentin , Hardness , Humans , Spectrum Analysis, RamanABSTRACT
One of the aims in the clinical operative management of dental carious lesions is to remove selectively the highly infected and structurally denatured dentine tissue, while retaining the deeper, repairable affected and intact, healthy tissues for long-term mechanical strength. The present study examined the correlation of chemical functional groups and the microhardness through the different depths of a carious lesion using Raman spectroscopy and Knoop microhardness testing. The null hypothesis investigated was that there was no correlation between Raman peak ratios (amide I : phosphate ν1 ) and equivalent Knoop microhardness measurements. Ten freshly extracted human permanent teeth with carious dentine lesions were sectioned and examined using high-resolution Raman microscopy. The ratio of absorbency at the amide I and phosphate bands were calculated from 139 scan points through the depth of the lesions and correlated with 139 juxtaposed Knoop microhardness indentations. The results indicated a high correlation (p < 0.01) between the peak ratio and the equivalent Knoop hardness within carious dentine lesions. This study concluded that Raman spectroscopy can be used as a non-invasive analytical technology for in vitro studies to discriminate the hardness of carious dentine layers using the peak ratio as an alternative to the invasive, mechanical Knoop hardness test.
ABSTRACT
BACKGROUND: Few data are available about the rate of short-term remission and its impact on the long-term outcomes of proliferative lupus nephritis in the Middle East. METHODS: An observational study was carried out involving 96 adult patients with biopsy-proven focal or diffuse proliferative lupus nephritis (PLN) from four different hospitals. Data on induction, remission and long-term outcomes were collected and analyzed. RESULTS: Among the 96 patients with biopsy-proven PLN (median age 27 (IQR: 21,34) years, 85% women and median duration of systemic lupus erythematosus (SLE) prior to diagnosis 27 (IQR: 11, 55) months), 67% developed remission at 6 months (proportion 0.67; 95% CI 0.57, 0.76). Mycophenolate mofetil (MMF) was used in 45/96 (47%), CYC in 41/95 (43%) and other agents in 10/96 (10%). The choice of MMF as induction agent has increased in recent years. Among baseline characteristics, only histologic activity was found to have a significant association with remission, with active lesions more likely to remit than active/chronic and chronic lesions (AOR 6.5, 95% CI 1.44-29.39, p = 0.015). Based on Kaplan-Meier analysis, the 5-year renal survival rate without doubling serum creatinine was 73.8%. Compared to patients with complete remission, lower long-term renal survival rates were observed in patients with no remission (89.7 versus 43%, p = 0.001) and partial remission (89.7 versus 77.6%, p = 0.256). The cumulative rate of doubling serum creatinine, dialysis, relapse and death was 23%, 11%, 10% and 5%, respectively, at 48-month median follow up. CONCLUSION: Approximately two-thirds of patients with PLN develop remission in response to standard induction therapy. Remission was negatively associated with the presence of chronic changes in renal biopsy. Overall, MMF is the most commonly used agent to induce remission; however, with more severe disease CYC, is used more frequently. PLN is associated with significant long-term renal outcomes including a 26% cumulative rate of doubling of serum creatinine at 5 years. Initial remission predicts this long-term renal survival.
