Odontogenic tumours in children and adolescents: a collaborative study of 431 cases

This study describes the oral and maxillofacial pathological characteristics of a series of odontogenic tumours in children and adolescents from three Brazilian reference centres. The records were reviewed for all odontogenic tumours in patients up to 18 years old based on criteria proposed by the World Health Organization (WHO) in 2005. Data concerning sex, age, skin colour and tumour location were collected and plotted. Four hundred and thirty one odontogenic tumours in children and adolescents were found, accounting for 37.5% of the total number of odontogenic tumours diagnosed. Benign tumours were predominant (99.8% of the cases), and odontoma was the most frequent type (41.4%), followed by keratocystic odontogenic tumours (25.5%) and ameloblastoma (14.6%). Odontogenic tumours were rarely detected in early childhood, and their prevalence increased with age. An almost equal distribution was observed with respect to sex and the site of the lesions. This study is the largest reported retrospective analysis describing odontogenic tumours in children and adolescents to date. The authors detected some variation in the relative frequency of odontogenic tumours compared with similar reports. Additional studies should be conducted based on the new WHO classification and predetermined age parameters to enable comparative analysis among different worldwide populations.     

Hydrogen peroxide release kinetics into saliva from different whitening products: a double-blind, randomized clinical trial

The objective of this study is to compare salivary hydrogen peroxide (HP) release kinetics and potential toxicity of systemic exposure of four different whitening products. A double-blind, randomized controlled trial was conducted in a Portuguese dental faculty clinic. Two hundred forty volunteers were randomized to eight intervention groups. Participants were randomly assigned to receive active or placebo applications of one of four different products: Opalescence 10% PF™ (OPL), Vivastyle? 10%™ (VS10%), Vivadent Paint On Plus™ (PO+), and Trés White Supreme™ (TWS). Saliva collection was obtained by established methods at different times. The HP salivary content was determined by a photometric method. Salivary HP variations, total amount of salivary HP, and counts of subjects above the safe daily HP dose were the main outcome measures. All whitening systems significantly released HP to the saliva when compared to placebo, and all showed different release kinetics. The adaptable tray system (TWS) presented a risk increase of 37% [20–54%, 95% confidence interval] when compared to the other systems. The use of an adaptable tray whitening system with higher concentration of HP increases the toxicity potential.     

Fracture strength of incisor crowns after intracoronal bleaching with sodium percarbonate

Abstract – Objectives: To compare the fracture resistance of bovine teeth after intracoronal bleaching with sodium percarbonate (SPC) or sodium perborate (SP) mixed with water or 20% hydrogen peroxide (HP). Materials and methods: Fifty extracted bovine teeth were divided into four experimental groups (G1–G4) and one control (n = 10) after endodontic treatment. Following root canal obturation, a glass ionomer barrier was placed at the cemento–enamel junction. After that, the pulp chambers were filled with: G1 – SP with water; G2 – SP with 20% HP; G3 – SPC with water; and G4 – SPC with 20% HP. No bleaching agent was used in the control group. Coronal access cavities were sealed with glass ionomer and specimens were immersed in artificial saliva. The bleaching agents were replaced after 7 days, and teeth were kept in artificial saliva for an additional 7 days, after which the pastes were removed and the coronal access cavities were restored with glass ionomer. Crowns were subjected to compressive load at a cross head speed of 0.5 mm min^?1 applied at 135° to the long axis of the root by an EMIC DL2000 testing machine, until coronal fracture. Data were statistically analysed by anova and Tukey test. Results: No differences in fracture resistance were observed between the experimental groups (P > 0.05). However, all experimental groups presented lower fracture resistance than the control group (P < 0.05). Conclusion: SPC and SP led to equal reduction on fracture resistance of dental crowns, regardless of being mixed with water or 20% HP.     

Rehabilitative treatment of cleft lip and palate: experience of the Hospital for Rehabilitation of Craniofacial Anomalies/USP (HRAC/USP)--Part 1: overall aspects

Cleft lip and palate is the most common among craniofacial malformations and causes several esthetic and functional implications that require rehabilitation. This paper aims to generally describe the several aspects related to this complex pathology and the treatment protocol used by the Hospital for Rehabilitation of Craniofacial Anomalies, University of S?o Paulo (HRAC-USP) along 40 years of experience in the treatment of individuals with cleft lip and palate.     

Effect of different investments and mold temperatures on titanium mechanical properties

PurposeThe aim of the present study was to evaluate commercially pure titanium (CP Ti) casting quality when a specific to titanium and a conventional phosphate bonded investments were used under different mold temperatures. For this, the evaluated parameters were surface roughness, bending strength, Vickers microhardness, casting quality by radiographies and microstructure of CP Ti.MethodsWax patterns (28 mm × 3 mm × 1 mm) were invested using two phosphate bonded investments: Rematitan Plus (REM), specific to titanium, and Castorit Super C (CAS), a conventional investment, fired and cooled until reaching two mold temperatures: 430 °C (430) and room temperature (RT). Specimens were cast from CP Ti by plasma. After casting, specimens were radiographically examined and submitted to Vickers microhardness, roughness and bending strength evaluation. Microstructure was analyzed in the center and at the surface of specimen.ResultsQualitative analysis of radiographs showed that specimens which were cast using CAS-RT presented more casting porosities while the specimens which were cast with REM-430 did not present any casting porosity. No significant difference was noted among the groups in the surface roughness and Vickers microhardness data, but the bending strength of the specimens cast using CAS was greater than REM groups. The microstructure of the specimens of the different groups was similar, presenting a feather-like aspect.ConclusionCasting porosities found in the specimens cast using conventional investments (CAS) and lower mold temperatures would limit their use, even mechanical properties were similar than in specimens cast using specific to titanium investment (REM) at temperatures recommended by the manufacturer.