Light Transmission through a Translucent Fiber Post Luís Fernando dos Santos Alves Morgan, DDS,* Rogéli Tiburcio Ribeiro da Cunha Peixoto, DDS, MSc,* Rodrigo de Castro Albuquerque, DDS, MSc, PhD,* Maurício Ferrari Santos Corrêa, DScEng, † Luiz Thadeu de Abreu Poletto, DDS, MSc, PhD,* and Marcos Barbosa Pinotti, DDS, MSc, PhD † Abstract This study is a quantitative assessment of the luminous energy transmitted through different translucent fiber posts. After embedding the posts in black resin, the blocks were submitted to sequential cuts in a precision machine, and depths of 16 mm, 12 mm, 8 mm, and 4 mm were assessed for light transmission with a digital photometer. The quantitative analysis showed signifi- cant differences between different posts and depths. Furthermore, the values obtained revealed that the quantity of luminous energy transmitted depends on the type of post and that for all of them there was a significant reduction of the quantity of light transmitted as the depth increased. Even without the post, the luminous intensity inside the canal seems to decrease to levels that are insufficient for polymerization, espe- cially in the apical third. (J Endod 2008;34:299 –302) Key Words Dental material, dental posts, light transmission, trans- illumination T here is a great variety of prefabricated posts, varying in their composition, anatomic form, and superficial configurations (1). Translucent posts have recently appeared on the market and are intended to conduct the light necessary to polymerize physical or dual-activation resin cements (2, 3). The adhesive technique for cementing fiber-reinforced intraradicular resin posts has been thoroughly studied by a number of authors (4–9). Use of adhesive techniques has limitations with respect to both technique and materials used according to Pirani et al. (6). Ferrari et al. (4) concluded that the variations in the density and orientation of the dentinal tubules in the different assessed areas are associated with the highest adhesion values observed in the cervical third followed by the middle and apical thirds. Because of these limitations, glass ionomer cements are also being investigated for such purposes (10). Fiber posts, including translucent ones, exhibit some interesting features justifying their clinical usage, which include an elasticity module similar to that of the dentine and chemical characteristics compatible with Bisphenol-Glycidyl Methacrylate (Bis-Gma) and with resins commonly used in adhesive procedures (11). The adhesive resistance seems to depend on the type of post (7). The decrease of the adhesive resistance in the apical thirds for resin cements is not clear (12, 13) but seems to be related to lower intensities of curing light at greater depths (14, 15). Recently, Mallmann et al. (16) suggested that if the halogen light passes through the translucent fiber post, this propagation does not have a significant influence on the adhesive resistance values. For this reason, it is necessary to study the effective ability of light to be transmitted along posts (17). The null hypothesis tested was that the trans- lucent post may be able to transmit light to depths sufficient for cure resin cements. Material and Methods Ten fiber posts of different manufacturers and translucencies were tested as shown in Table 1. A 15  31 mm hollow plastic device was used, with 2 central orifices in opposing faces to guide each post into the long axis of the device, and crystal resin with black pigment was poured into the device by using a mechanical vibrator (Vibramolde; RHOS, Duque de Caxias, RJ, Brazil) to eliminate voids, which resulted in standardized 14  18 mm blocks. Because the posts to be tested had different lengths, all were cut to leave 2 mm protruding from the surface of the resin block, standardizing the length of posts at 16 mm (Fig. 1). For the control group, a crystal resin block was filled with the White Post DC (FGM, Joinville, SC, Brazil) post, which was lubricated for its later removal. In this way, a resin block with an internal hollow orifice was obtained without the post. After casting and preparing the blocks, readings for the passage of light were made at the apical limit, apical third, middle third, and cervical third, involving post lengths of 16, 12, 8, and 4 mm respectively. To obtain readings, the specimens were progressively cut in an ISOMET 1000 (Buehler, Lake Bluff, IL) machine, complying with manufac- turer’s cooling specifications and removing material from the apical surface of the blocks. The specimens were inserted in a metallic apparatus that maintained the relation between the light source, the specimen, and the digital reader (Nova; Ophir, Hicksville, NY). This apparatus was custom made to precisely hold the block for each measure- ment depth and was therefore in three parts (Fig. 1). From the Departments of *Restorative Dentistry and † Me- chanical Engineering, Federal University of Minas Gerais, Belo Horizonte, Brazil. Address requests for reprints to Dr Luís Fernando dos Santos Alves Morgan, Department of Restorative Dentistry, Federal University of Minas Gerais, Belo Horizonte, Brazil. E-mail address: luismorgancd@yahoo.com.br. 0099-2399/$0 - see front matter Copyright © 2008 by the American Association of Endodontists. doi:10.1016/j.joen.2007.12.007 Basic Research—Technology JOE — Volume 34, Number 3, March 2008 Light Transmission through a Translucent Fiber Post 299