Correlation between Volume of Apical Periodontitis Determined by Cone-beam Computed Tomography Analysis and Endotoxin Levels Found in Primary Root Canal Infection Fl  avia G.R. Cardoso, DDS, MSc, PhD,* N adia S. Ferreira, DDS, MSc,* Frederico C. Martinho, DDS, MSc, PhD,* Gustavo G. Nascimento, DDS, MSc, † Luiz R.C. Manh~ aes, Jr, DDS, MSc, PhD, ‡ Marco A. Rocco, DDS, MSc, PhD, ‡ Cl  audio A.T. Carvalho, DDS, MSc, PhD,* and Marcia C. Valera, DDS, MSc, PhD* Abstract Introduction: This clinical study was conducted to correlate the levels of endotoxins and bacterial counts found in primary endodontic infection with the volume of periapical bone destruction determined by cone- beam computed tomography (CBCT) analysis. Moreover, the levels of bacteria and endotoxins were correlated with the development of clinical features. Methods: Twenty-four root canals with primary endodontic dis- ease and apical periodontitis were selected. Clinical fea- tures such as pain on palpation, pain on percussion, and previous episode of pain were recorded. The volume (cubic millimeters) of periapical bone destruction was determined by CBCT analysis. Endotoxins and bacterial samplings were collected by using sterile/apyrogenic pa- per points. Endotoxins were quantified by using limulus amebocyte lysate assay (KQCL test), and bacterial count (colony-forming units [CFU]/mL) was determined by us- ing anaerobic culture techniques. Data were analyzed by Pearson correlation and multiple logistic regression (P < .05). Results: Endotoxins and bacteria were de- tected in 100% of the root canal samples (24 of 24), with median values of 10.92 endotoxin units (EU)/mL (1.75–128 EU/mL) and 7.5  10 5 CFU/mL (3.20  10 5 –8.16  10 6 CFU/mL), respectively. The median vol- ume of bone destruction determined by CBCT analysis was 100 mm 3 (10–450 mm 3 ). The multiple regression analysis revealed a positive correlation between higher levels of endotoxins present in root canal infection and larger volume of bone destruction (P < .05). More- over, higher levels of endotoxins were also correlated with the presence of previous pain (P < .05). Conclu- sions: Our findings revealed that the levels of endo- toxins found in root canal infection are related to the volume of periapical bone destruction determined by CBCT analysis. Moreover, the levels of endotoxin are related to the presence of previous pain. (J Endod 2015;41:1015–1019) Key Words Bacteria, CBCT, endotoxins, infection A pical periodontitis is an inflammatory disorder established in periapical tissues as a result of root canal infection that culminates in periapical bone destruction (1). The gradual decrease in bone mineral density mediated by apical periodontitis appears on the radiograph as a radiolucent area around a root apex (2, 3). Lipopolysaccharide (LPS), also known as endotoxin, an outer membrane compo- nent of gram-negative bacteria predominantly involved in root canal infection (4, 5), is an important inflammatory mediator in apical periodontitis (6–8). The LPS molecule has been shown to interact with local tissue cells via toll-like receptors (TLRs), both TLR-2 and TLR-4 (8), which in turn recognize the LPS molecule and activate multiple downstream signaling pathways (5, 9, 10). The binding of LPS to TLR-4 leads to the activation of p38 mitogen-activated protein kinase (an upstream effector common to many inflammatory cytokines), whereas the nuclear factor kappa B transcription factor (central to several immune and inflammatory responses) leads to the release of bone resorptive mediators that participate in bone destruction (5, 9–11). Over the years, many clinical studies have attempted to investigate the presence of endotoxins in root canal infection with apical periodontitis (6–8, 12, 13) and to correlate its contents with the development of clinical features (7, 8, 14) and size of bone destruction (6–8, 11). Higher levels of bacteria and endotoxins (6, 11, 12) have been found in teeth with larger size of radiolucent area. However, all these previous studies determined the size of periapical radiolucency by using 2-dimensional (2D) periapical radiographs, which is quite insufficient, especially because of the lack of capacity of this 2D method in assessing the ‘‘depth’’ (buccolingual size) of a lesion (15–17). With the introduction of the 3-dimensional (3D) reconstruction of an anatomic area at a relatively low radiation dose, it became possible to use cone-beam computed tomography (CBCT) (15, 17). As an advantage, CBCT imaging can distinguish which roots are involved in the lesion as well as their exact location and volume of bone destruction (15, 18). To our knowledge, however, there has been no clinical report From the *Department of Restorative Dentistry, Endodontic Division; and ‡ Department of Radiology, S~ ao Jos e dos Campos Institute of Science Technology, Univer- sidade Estadual Paulista (UNESP), S~ ao Jos e dos Campos, S~ ao Paulo; and † Department of Semiology, Federal University of Pelotas, School of Dentistry, Pelotas, Rio Grande do Sul, Brazil. Address requests for reprints to Dr Marcia C. Valera, Department of Restorative Dentistry, Endodontic Division, S~ ao Jos e dos Campos Institute of Science Technology, Universidade Estadual Paulista (UNESP), Eng Francisco Jos e Longo, 777, CEP 12245-000 S~ ao Jos e dos Campos, SP, Brazil. E-mail address: marcia@fosjc.unesp.br 0099-2399/$ - see front matter Copyright ª 2015 American Association of Endodontists. http://dx.doi.org/10.1016/j.joen.2015.02.005 Clinical Research JOE — Volume 41, Number 7, July 2015 Volumetric Apical Periodontitis and Endotoxins 1015