Evaluation of Dental Enamel Mass in Prolonged Supervised Dental Bleaching Protocol with Calcium-Containing Gel

ABSTRACT: The objective of this study was to determine the enamel mass variation after a prolonged bleaching treatment using a calcium-containing 4% hydrogen peroxide gel Twenty sound bovine incisors were randomly assigned to two groups (n=10) stored in G1) distilled water and G2) artificial saliva. An electronic analytic scale (.000 grams measurements) was used to determine the enamel mass variation before and after the bleaching procedures at the following evaluation times: T0) before the bleaching procedures; T1) 14 days of treatment, as instructed by the manufacturer; T2) 21 days of treatment, 50 % beyond what is instructed by the manufacturer; and T3) 28 days of treatment, 100 % beyond what is instructed by the manufacturer. The highest mean was observed at T2/G2 (0.3259 g) and the lowest at T2/G1 (0.3265 g). The specimens stored in distilled water (G1) showed 6 % mass reduction when T0 (0.3277 g) was compared to T3 (0.3277 g). On the other hand, the specimens stored in artificial saliva exhibited a significant mass increase of 19 % when T0 (0.3521 g) was compared to T3 (0.3528 g). Prolonged bleaching therapy using 4 % hydrogen peroxide with calcium resulted in a massive reduction when water was used as a storage medium. When the specimens were stored in artificial saliva, an increase in mass was observed, probably due to the mineralizing properties of the artificial saliva.

RESUMEN: El objetivo de este estudio fue determinar la variación de la masa del esmalte después de un tratamiento de blanqueamiento prolongado utilizando calcio conteniendo un gel de peróxido de hidrógeno al 4 %. Veinte incisivos bovinos intactos fueron asignados aleatoriamente a dos grupos (n-10) almacenados en G1 - agua destilada y G2- saliva artificial. Se utilizó una escala analítica electrónica (.000 gramos) para determinar la variación de la masa de esmalte antes y después de los procedimientos de blanqueamiento en los siguientes tiempos de evaluación: T0) antes de los procedimientos blanqueadores; T1) 14 días de tratamiento, según las instrucciones del fabricante; T2) 21 días de tratamiento, 50 % más allá del tiempo indicado por el fabricante; y T3) 28 días de tratamiento, 100 % más allá del tiempo indicado por el fabricante. La media más alta se observó en T2/G2 (0,3259 g) y la más baja en T2/G1 (0,3265 g). Los especímenes almacenados en agua destilada (G1) mostraron una reducción de masa del 6 % cuando se comparó T0 (0,3277 g) con T3 (0,3277 g). Por otro lado, los dientes almacenados en saliva artificial mostraron un aumento significativo de masa del 19 % cuando se comparó T0 (0,3521 g) con T3 (0,3528 g). La terapia de blanqueamiemto prolongado con calcio conteniendo un gel de peróxido de hidrógeno al 4 % condujo a una reducción masiva cuando se utilizó agua como medio de almacenamiento, mientras que los dientes almacenados en saliva artificial mostraron un aumento en la masa, probablemente debido a las propiedades remineralizadoras de la saliva artificial.

Do HEMA-free adhesive systems have better clinical performance than HEMA-containing systems in noncarious cervical lesions? A systematic review and meta-analysis.

OBJECTIVES: To determine through a systematic review whether HEMA-free adhesive systems have better clinical performance than HEMA-containing systems in noncarious cervical lesion (NCCL) restorations. SOURCES: We systematically searched PubMed, The Cochrane Library, Scopus, Web of Science, and Open Grey databases using MeSH terms, synonyms, and keywords, with no language or date restriction. The reference lists of included articles were manually searched. STUDY SELECTION: Randomized controlled clinical trials comparing the effectiveness of HEMA-free and HEMA-containing adhesive systems in NCCL restorations were included. The risk of bias in the included studies was assessed and classified through the Cochrane Collaboration's common scheme for bias. Quantitative data were subgrouped according to the main clinical parameters evaluated, and heterogeneity was tested using I2 index. DATA: A total of 2889 potentially relevant studies were identified. After title and abstract examination, 51 studies remained. Finally, 22 studies were included in the systematic review, totaling to 997 participants. Thus, 13 studies were classified as "low" risk of bias and nine as "unclear". These 22 studies were also included in the meta-analysis, and no significant statistical difference was found between the clinical performances of HEMA-free and HEMA-containing adhesive systems for all parameters analyzed: retention risk difference (RD) 0.03 [-0.01, 0.07] (p = 0.13); marginal discoloration RD 0.02 [-0.01, 0.04] (p = 0.19); marginal adaptation RD -0.01 [-0.04, 0.01] (p = 0.34); caries RD 0.00 [-0.01, 0.01] (p = 0.92); or postoperative sensitivity RD -0.00 [-0.02, 0.01] (p = 0.72) and for overall effect RD 0.00 [-0.01, 0.01] (p = 0.65). CONCLUSIONS: HEMA-free and HEMA-containing adhesive systems showed a similar clinical performance in NCCL restorations. CLINICAL SIGNIFICANCE: Only the presence of HEMA does not indicate better clinical performance of adhesive systems.

Squamous cell carcinoma of the tongue and floor of the mouth: analysis of survival rate and independent prognostic factors in the Amazon region.

Oral squamous cell carcinoma (OSCC) accounts for more than 95% of all malignant neoplasms in the oral cavity. Although several studies have shown the epidemiology of this cancer in Brazil, there do not seem to be any studies that describe the prognostic factors related to OSCC in the Amazon region. Therefore, the aim of this study was to determine the survival rate and prognostic significance of different factors in patients from this region affected by OSCC. Data from 85 patients with histologically confirmed squamous cell carcinoma of the tongue and floor of the mouth identified from the Ofir Loyola Hospital archives were collected and analyzed using univariate (log-rank test) and multivariate (Cox proportional hazard model) tests. The overall 5-year survival rate was found to be 27%. Univariate analysis showed that the 5-year survival rate was significantly higher for younger (≤ 45 y) female patients, patients with T1-2 tumors and clinically clear neck nodes (N0), patients with early stage cancers (AJCC stage I-II), and patients treated with surgical procedures. However, multivariate analysis showed that the 5-year survival rate was significantly higher only in the younger patients and those who underwent surgical treatment. The age of the patient at the moment of diagnosis and treatment with surgical procedures were the only independent prognostic factors that affected the 5-year survival rate of the patients in this region.