Molars Fracture Resistance with Class II Cavities Restored with Different Resin - Based Materials

The teeth weakening due to the preparation of class II mesio-occluso-distal cavities is a challenge for the clinician. The objective of this study was to evaluate the molars fracture resistance with class II mesio-occluso-distal cavities restored with different restorative techniques and materials. Forty extracted molars were divided into 5 groups: Group 1 – intact healthy teeth (positive control); Group 2 – unrestored teeth with mesio-occluso-distal class II cavities (negative control); Groups 3 to 5 – restored teeth with standardized dimensions. In groups 3 to 5, the cavities were restored with flow resin only, flow resin coated with a nano-hybrid resin, and nano-hybrid resin only, respectively. All specimens were tested for resistance to fracture using an axial compressive load, a metallic sphere measuring 8 mm in diameter on a universal testing machine EMIC DL-2000. A 10 kN load cell operated at a speed of 5 mm/min until the tooth fracture. Data were subjected to analysis of variance and Tukey’s tests (α = 0.05). Group 3 showed higher fracture strength (2243.1 ± 473.7N) when compared to groups 2, 4 and 5. This difference was statistically significant (p<0.05). The fracture strength of teeth restored with flow mesio-occluso-distal restorations was similar to that of intact natural teeth. Keywords: Compressive Strength. Composite Resins. Dental Cavity Preparation. ResumoO enfraquecimento dos dentes devido às preparações de cavidades mesio-ocluso-distal é um desafio para o clínico. O objetivo deste estudo foi avaliar a resistência à fratura de molares com cavidades mesio-ocluso-distais classe II restauradas com diferentes técnicas e materiais restauradores. Quarenta molares extraídos foram divididos em 5 grupos: Grupo 1 – dentes saudáveis intactos (controle positivo); Grupo 2 – dentes não restaurados com cavidades mesio-occluso-distais classe II (controle negativo); Grupos 3 a 5 – dentes restaurados com dimensões padronizadas. Nos grupos 3 a 5, as cavidades foram restauradas apenas com resina flow, resina flow recoberta com uma resina nano-híbrida e somente resina nano-híbrida, respectivamente. Todas as amostras foram testadas quanto à resistência à fratura usando uma carga compressiva axial, usando uma esfera metálica medindo 8 mm de diâmetro em uma máquina de teste universal EMIC DL-2000. Uma célula de carga de 10 kN operava a uma velocidade de 5 mm/min até a fratura do dente. Os dados foram submetidos à análise de variância e testes de Tukey (α = 0,05). O grupo 3 apresentou maior resistência à fratura (2243,1 ± 473,7N) quando comparado aos grupos 2, 4 e 5. Essa diferença foi estatisticamente significante (p <0,05). A resistência à fratura dos dentes restaurados com resina flow foi semelhante à dos dentes naturais intactos. Keywords: Força Compressiva. Resinas Compostas. Preparo da Cavidade Dentária.

Laser Treatment Based on Minimal Intervention - Report of Cases

Since the development of the ruby laser by Maiman in 1960, many lasers are available today for clinical application in dentistry, based on minimally invasive (Ml) dental treatment in routine clinical procedures including dental cavity preparation, removal of dental calculus, caries prevention, and treatment of dentin hypersensitivity, anti-iriflammation for soft tissues, pain relief, surgical operations, and hemostasis. Dental treatment using a laser is a minimally invasive, painless treatment with a low burden on the patient, and may therefore be seen as a treatment that complies with the Ml concept. However, safe use of lasers must be the underlying goal of proposed or future laser therapy. To ensure that safe, effective Ml treatment is practiced when using lasers, it is essential to have a full understanding of their advantages and disadvantages before using them. DOI: http://dx.doi.org/10.3329/bjdre.v4i2.20257 Bangladesh Journal of Dental Research and Education Vol.4(2) 2014: 91-93

Influence of the power level of an ultra-sonic system on dental cavity preparation

The aim of this study was to evaluate the shape of dental cavities made with the CVDentus® system using different ultrasound power levels. One standard cavity was made on the buccal aspect of 15 bovine incisors with a CVDentus® cylindrical bur (82142). The sample was divided into three groups: G1 - ultrasound with power II; G2 - ultrasound with power III; and G3 - ultrasound with power IV. A standardizing device was used to obtain standardized preparations and ultrasound was applied during one minute in each dental preparation. The cavities were sectioned in the middle, allowing observation of the cavity’s profile with a magnifying glass, and width and depth measurement using the Leica Qwin program. The Kruskal-Wallis (p < 0.05) and Dunn statistical analyses demonstrated differences between the dental cavity shapes when powers III and IV were used. However, the cavities that were made with power III presented dimensions similar to those of the bur used for preparation. We concluded that the power recommended by the manufacturer (III) is the most adequate for use with the CVDentus® system.