Effect of the Photo-initiator System Contained in Universal Adhesives on Radicular Dentin Bonding

CLINICAL RELEVANCE

The photo-initiator system based on an advanced polymerization system may be an alternative that can be used to overcome the disadvantages of radicular dentin, especially for the apical third.

SUMMARY

Objectives: The purpose of this study was to evaluate the effects of universal adhesives with different photo-initiator systems applied in etch-and-rinse (ER) and self-etch (SE) modes on dentin interaction (push-out bond strength [PBS], nanoleakage [NL], and degree of conversion [DC] within the hybrid layer) in the different root thirds after fiber post cementation.Methods and Materials: Roots of endodontically prepared human premolars were randomly divided into six groups according to one of three adhesive systems (Scotchbond Universal [SBU], Ambar Universal [AMB], and Ambar Universal APS [AMB-APS]) and two adhesive strategies (ER and SE) for each system. Posts were cemented, and PBS was tested at 0.5 mm/min. The NL was evaluated by scanning electron microscopy. DC was measured using micro-Raman spectroscopy. The data were analyzed by three-way analysis of variance and Tukey tests (α=0.05).Results: AMB-APS showed similar performance in all root thirds (p>0.05) and higher values of DC, especially in the apical third (p<0.0001). AMB and SBU showed the lowest values in the apical third (p<0.0001).Conclusions: The APS photo-initiator system contained in universal adhesives is a feasible alternative for improving radicular bonding procedure.

Impact of root canal preparation performed by ProTaper Next or Reciproc on the quality of life of patients: a randomized clinical trial

AIM

To compare the impact of the two different root canal preparation systems on the quality of life of patients and correlate postoperative pain with the impact on quality of life.

METHODOLOGY

A randomized clinical trial was conducted with 58 patients allocated into two groups based on the root canal preparation system employed: ProTaper Next (PN) or Reciproc (R). Data collection involved the administration of a questionnaire addressing demographic and clinical characteristics, the OHIP-14 (quality of life) and a visual analog scale (pain). The latter two were the outcomes of interest and were administered in the first 24 h after root canal treatment. The data were submitted to descriptive analysis, bivariate analysis, Poisson univariate and multiple regression, and Spearman's correlation test, with a 5% significance level.

RESULTS

A greater frequency of impact after treatment was found for the items 'uncomfortable to eat food' and 'felt self-conscious'. No significant difference between groups was found regarding the severity of impact for total OHIP-14 score or any of the domain scores.

CONCLUSIONS

The two root canal preparation systems exerted a similar impact on quality of life. Postoperative pain was correlated with impact on quality of life, affecting chewing function, self-consciousness and stress. Thus, it is important for dentists to provide care capable of preventing or treating the negative consequences of such therapy.

Efeito de Soluções de Reumedecimento na Resistência de União de Materiais Endodônticos Biocerâmicos

Avaliar a influência de soluções de reumedecimento sobre a resistência de união à dentina radicular de uma guta-percha convencional (GP) e um composto experimental à base de vidro niobofosfato bioativo e guta-percha (GNB) associado a um cimento biocerâmico. Condutos de 80 pré-molares inferiores foram preparados utilizando instrumentos de NiTi e irrigação com hipoclorito de sódio e EDTA foram divididos aleatoriamente em quatro grupos segundo guta-percha utilizada: GNB ou GP associada com Endosequence BC Sealer- BC e solução de reumedecimento antes da obturação (água destilada - AD solução salina de tampão fosfato - PBS fluido corporal simulado - SBF ou sem solução - controle). Os espécimes foram obturados com cone único e condensação vertical. Após 30 dias, foram seccionados em fatias e realizado o teste de push-out para avaliar a resistência de união e o tipo de fratura analisado com lupa estereoscópica. Os dados foram analisados por two-way ANOVA e teste de Holm-Sidak (p<0,05). Houve diferença significativa para os tipos de guta-percha (P<0,001) e para as soluções de reumedecimento (p0,003). Interação guta-percha vs. soluções de reumedecimento não foi significativa (p 0,53). Solução de SBF proporcionou um aumento na resistência de união para a guta-percha. Associação de GNB+BC aumentou os valores de resistência de união quando comparados com a GP+BC. Uso de SBF aumentou os valores de resistência de união dos grupos estudados. Associação de GNB+BC foi benéfica, aumentando os valores de resistência de união de dentina quando comparado com a associação com GP.Palavras-chave: Endodontia. Guta-Percha. Materiais Biomiméticos.

Pinpi'n and pinpii'n multilayer devices with voltage controlled optical readout

In this paper we present results on the optimization of a pinpii'n type a-Si:H based three color detector with voltage controlled spectral sensitivity. The sensor element consists on a glass/ITO/p-i-n a-SiC:H multilayer structure which faces the incident illumination, followed by a-SiC:H(-p)/a-SiC:H(-i)/Si:H(-i')/SiC:H(-n)/ITO heterostructure, that allows the optically addressed readout. Results show that this approach leads to regionally different collection parameters resulting in multispectral photodiodes, coding for red (R), blue (B), and two green (G) components. In the polychromatic operation mode different sensitivity ranges are selected by switching between different biases so that the basic colors can be resolved with a single device. Positive bias is needed under blue irradiation and moderate reverse bias under green. The threshold voltage between green and red sensitivity depends on the thickness of the bottom a-SiC:H (-i) layer, and corresponds to the complete confinement of the absorbed green photons across the pinpi sequence. As the thickness of the a-Si:H i'-layer increases, the self-reverse effect due to the front absorption will be balanced by the decrease of the self-forward effect due to the back absorption shifting the threshold voltage to lower reverse bias. The various design parameters are discussed and supported by a numerical simulation.