Apical Granulomas Research Articles

Chronic maxillary rhinosinusitis of dental origin: a systematic review of 674 patient cases.

Objectives. The aim of this systematic review is to study the causes of odontogenic chronic maxillary rhinosinusitis (CMRS), the average age of the patients, the distribution by sex, and the teeth involved. Materials and Methods. We performed an EMBASE-, Cochrane-, and PubMed-based review of all of the described cases of odontogenic CMRS from January 1980 to January 2013. Issues of clinical relevance, such as the primary aetiology and the teeth involved, were evaluated for each case. Results. From the 190 identified publications, 23 were selected for a total of 674 patients following inclusion criteria. According to these data, the main cause of odontogenic CMRS is iatrogenic, accounting for 65.7% of the cases. Apical periodontal pathologies (apical granulomas, odontogenic cysts, and apical periodontitis) follow them and account for 25.1% of the cases. The most commonly involved teeth are the first and second molars. Conclusion. Odontogenic CMRS is a common disease that must be suspected whenever a patient undergoing dental treatment presents unilateral maxillary chronic rhinosinusitis.

Specificity of paediatric jawbone lesions: Tumours and pseudotumours

IntroductionCharacteristics and epidemiology of jaw tumours have been described mostly in adults. Compared with their adult counterparts, childhood jaw tumours show considerable differences. The aim of this study was to describe the different jaw tumours in children, define diagnostic tools to determine their specificity and describe optimal treatment. MethodsAll children patients with jaw lesions, excluding cysts, apical granuloma and osteitis were included in our study between 1999 and 2009. The medical records were analyzed for clinical, radiological, and pathological findings, treatments and recurrences. ResultsMean patient age was 10.9 years old, ranging from 2 months to 18 years old. Of the 63 lesions, 18 were odontogenic and 45 non-odontogenic lesions. 6% of all cases were malignant tumours; the mean age of presentation was 7.25 years old, [ranging from 0.2 to 18 years old]. Approximately 80% of the tumours developed after 6 years of age. Odontogenic tumours occurred more often after the age of 6. ConclusionCompared with their adult counterpart, childhood jaw tumours show considerable differences in their clinical behaviour and radiological and pathological characteristics. Clinical features of some tumours can be specific to children. Tumourigenesis is related to dental development and facial growth. Conservative treatment should be considered.

Expression of antimicrobial peptides and E-cadherin in periapical lesions

ObjectiveRadicular cysts and apical granulomas are inflammatory diseases that develop in association with an infected root canal. It is thought that persistent inflammation may stimulate proliferation of dental epithelial cells around the root to form a cyst. However, pathogenesis and the mechanism of epithelial proliferation have not been clarified. The purpose of this study is to examine the levels of chemical and physical antimicrobial activities of periapical lesions. MethodsTo explore the expression of antimicrobial peptides (AMPs) and E-cadherin in periapical lesions, 10 tissue specimens each of apical granulomas and radicular cysts were evaluated by immunohistochemistry using anti-AMPs [human neutrophil defensin (HNP), LL37, human beta-defensin (HBD)-1 and -2] and anti-E-cadherin antibody. In vitro assay to assess the expression of LL37, HBD-1, -2 and E-cadherin in the immortalized rat dental epithelial cell line (HAT-7) stimulated with/without lipopolysaccharide (LPS) or bacterial cells were detected by immunocytochemistry, quantitative real-time polymerase chain reaction and Western blot analysis. Cell proliferation after incubation with/without LPS or LL37 was assayed by MTT assay. ResultsHNP and LL37 were observed mainly in the neutrophils of apical granulomas, while HBD-1 and E-cadherin showed higher expression in radicular cysts than in apical granulomas. In vitro assays showed that bacterial stimulation enhanced expression of HBD-2, LL37, and E-cadherin, but epithelial cell proliferation was not enhanced with LPS and LL37. ConclusionsThese observations suggest that dental epithelial cells can secrete AMPs and consolidate epithelial intercellular junctions when stimulated by bacterial infection, and radicular cysts may play an important role in defense mechanisms.

Bacterial Distribution in Teeth with Pulp Necrosis and Apical Granuloma

ABSTRACT Aim To evaluate the distribution of bacteria in teeth with pulp necrosis and apical granuloma. Materials and methods Thirty-two extracted teeth with pulp necrosis and apical granulomas and 16 cases of isolated apical granulomas were sectioned and stained with Hematoxylin and Eosin (H&E) and Brown-Brenn staining for microscopic evaluation. The specimens were observed as to the location and distribution of bacteria involved in the process of pulp necrosis and their relationship with the periapical tooth structures and soft tissues. Results Stainable Gram-positive and Gram-negative bacteria were found in the entire root canal system. Bacterial biofilms were detected in 81.2% of cementum root canal, 46.8% in apical delta, 65.6% at the apical surface and 79.2% of the granulomas above all the specimens. Bacteria and bacterial biofilms were present in the entire root canal system of the infected teeth with apical granulomas. Conclusion Our findings suggest that bacterial infections can reach inaccessible areas to instrumentation. How to cite this article Ribeiro FC, Consolaro A, Pinheiro TN. Bacterial Distribution in Teeth with Pulp Necrosis and Apical Granuloma. Int J Experiment Dent Sci 2013;2(2):86-91.

Expression of interleukin-17F in human apical periodontitis lesions

To examine the expression of interleukin-17F (IL-17F) in apical periodontitis lesions. Human apical periodontitis lesions were collected after periapical surgery from November 1, 2009 to August 1, 2011. After histological processing, serial sectioning, HE staining, and microscopic analysis, 33 periapical cysts and 18 periapical granulomas were selected for immunohistochemical analysis for IL-17F. Five alveolar bone samples were obtained from a group of impacted third molars recommended for extraction. These bone samples did not show any inflammation and were used as normal samples. Differences in IL-17F expression between the tissues with periapical cyst and periapica granuloma were subsequently analyzed by rank-sum test. IL-17F was expressed in epithelial cells, lymphocytes, fibroblast and endothelial cells of both types of lesions. Both types of lesions presented increased IL-17F expression when compared to healthy periapical alveolar bone. The expression of IL-17F in apical cyst (0.2365 ± 0.0708) and apical granuloma (0.8852 ± 0.0576) was significantly different (Z = 3.735, P < 0.01). IL-17F could be observed and might be involved in the inflammatory response and bone resorption of periapical tissues. The expression of IL-17F in periapical cyst and periapical granuloma was significantly different.

Frequency and Distribution of Radiolucent Jaw Lesions: A Retrospective Analysis of 9,723 Cases

ObjectivesPractitioners should be aware of the occurrence rate and usual location of radiolucent jaw lesions. The aims of this study were to examine the frequency and location of radiolucent jaw lesions, including apical granulomas, apical cysts, keratocystic odontogenic tumors (KOTs), central giant cell lesions (CGCLs), ameloblastomas, and metastatic lesions, that were submitted for biopsy along with associated demographics. MethodsBiopsy diagnoses from 9,723 lesions (submitted between 1992 and 2006) were included in this study. Data on lesion location as well as patient demographics were evaluated. ResultsThirty types of radiolucent jaw lesions were classified. Nonhealing apical granulomas (40.4%) and cysts (33.1%) occurred at similar rates and together totaled 73% of all biopsied lesions. The majority of reported granulomas and cysts occurred in the anterior maxilla (>36% in each category). The frequency of KOTs (8.8%), CGCLs (1.3%), ameloblastomas (1.2%), and metastatic lesions (<1%) are to be noted along with their location, which was predominately in the posterior mandible. The occurrence of apical cysts, ameloblastomas, KOTs, and metastatic lesions were seen slightly more in men, at 56%, 54%, 55%, and 68%, respectively. The occurrence of CGCLs was seen slightly more in women at 56%, whereas apical granulomas were equally present in men and women. ConclusionsMost nonhealing lesions submitted for biopsy were classified as granulomas or cysts (73%) often from the anterior maxillary jaw. Nonhealing radiolucent jaw lesions other than granulomas or cysts were reported over 20% of the time and may have more severe pathological implications, suggesting the value of differential diagnoses.

Case report: endodontic and surgical treatment of an upper central incisor with external root resorption and radicular cyst following a traumatic tooth avulsion

In the age group between 6 and 12 years, trauma to the upper incisors happens frequently. In the case of avulsion, a replantation is the state-of-the-art treatment; however, it may lead to several complications, particularly if suitable posttraumatic management is not carried out. External cervical resorptions as well as apical granuloma and cysts due to microbial contamination of the root canal are common complications. In the presented trauma case, a conservative approach was chosen to treat a large cystic lesion combined with cervical and apical resorptions. After initial placement of Ledermix and calcium hydroxide into the root canal, a marsupialization with the temporary insertion of an obturator was performed. The gradual reduction led to a fast recovery of the bony defect and a root canal filling was placed. The 2-year follow-up showed an improved condition. All adjacent teeth remained vital during the course of the treatment.

Monocyte chemotactic protein‐3: possible involvement in apical periodontitis chemotaxis

To study the expression of monocyte chemotactic protein-3 (MCP-3, also known as chemokine CCL-7) in tissue from apical lesions (AL) and to associate MCP-3 expression with symptomatic or asymptomatic apical periodontitis. To determine the expression of MCP-3 in AL, biopsies obtained during tooth extraction procedures were fixed, subjected to routine processing and diagnosed as apical granuloma (AG) (n = 7) or radicular cyst (RC) (n = 5). As controls, apical periodontal ligament (PDL) specimens from healthy premolars extracted for orthodontics reasons were included (n = 7). All specimens were immunostained for MCP-3 and examined under a light microscope. In addition, homogenates from AL (n = 14) and healthy PDL samples (n = 7) were studied through immunowestern blot. Finally, periapical exudates samples were collected from root canals of teeth having diagnosis of symptomatic (n = 14) and asymptomatic apical periodontitis (n = 14) during routine endodontic treatments and analysed by immunowestern blot and densitometry. MCP-3 was detected in AG and RC and localized mainly to inflammatory leucocytes, whereas no expression was observed in healthy PDLs. MCP-3 was also detected in periapical exudate, and its levels were significantly higher in symptomatic than in asymptomatic apical periodontitis. MCP-3 was expressed in AL and its levels associated with clinical symptoms. MCP-3 might play a role in disease pathogenesis, possibly by stimulating mononuclear chemotaxis.

Clinical morphological estimation of the apical granulom before treatment chronic periodontitis in the aggravation and remission stage

Tissues of apical granulomas at the exacerbation and remission stages before and after the treatment with the use of transcanal electrogranulotomy (TCEGT) have been studied by the methods of histological and clinical X-ray investigations and nonparametric statistics. The content of polymorphonuclear leukocytes at the exacerbation doubled compared to the remission (p &lt; 0,05). After the treatment at the exacerbation stage (87 teeth) and beyond it (116 teeth), the activation of macrophages and fibroblasts was observed, as well as the appearance of Malassez's epithelial rests. The reconstruction of the bone structure has been found by the X-ray investigation in 97,6% of patients in the period up to 5 years. The treatment of granulomatous periodontitis with TCEGT is possible at any stage.

Expresión de Factor Estimulante de Colonias-1 (CSF-1) y Catepsina-K en Lesiones Periapicales

Periapical Lesions (PLs) represent an immunoinflammatory disease of infectious origin, characterized by periapical tissue destruction. PLs are linked to the expression of various inflammatory mediators: Colony Stimulating Factor-1 (CSF-1) that stimulates differentiation of osteoclast precursor cells and Cathepsin K, an enzyme associated with bone destruction, could be related to osteolysis during PL. The aim of this study was to characterize the expression of these mediators in inflammatory radicular cyst, periapical granuloma and healthy periodontal tissue. Materials and MethodsWe selected 13 individuals with clinical diagnosis of Apical Periodontitis (AP) and indication of extraction. Healthy subjects having indication of extraction for orthodontic reasons were also included. After extraction, specimens were biopsied and histological diagnosis was made. Subsequently, immunohistochemical staining was carried out to identify the mediators in study, and finally the samples were examined in a light microscope. ResultsCSF-1 and Cathepsin K expression was distributed similarly in apical granulomas and radicular cysts. They were mainly immunolocalized to inflammatory infiltrates. Also lining epithelium, cyst capsule, and vascular endothelium were mildly immunopositive. No immunoreactivity was observed in healthy periodontium. ConclusionsCSF-1 and Cathepsin K are expressed in PLs and may participate in the pathogenesis of AP

Expresión de CCL-7 y CCR-5 en Lesiones Periapicales

IntroductionOne of the key phenomena in Apical Lesions (AL) pathogenesis is chemotaxis. CCL-7 is a very potent chemoattractant for monocytes, and CCR-5 corresponds to one of its receptors. Until now, CCL-7 and CCR-5 expression in AL remains unknown. ObjectivesTo study the expression of CCL7 and CCR-5 in AL. MethodsPeriapical exudates (PE) samples were collected from root canals during routine endodontic treatments from teeth with diagnosis of symptomatic (n=15) and asymptomatic Apical Periodontitis (AP) (n=15), and “immunowestern blot” was conducted to assess the expression of CCL-7. The intensity of the bands was measured by densitometric analysis. As controls, homogenized tissue from healthy periapical ligaments was obtained during teeth extraction for orthodontic reasons (n=10). To determine the expression of CCL-7 and CCR-5 in AL, biopsies from teeth with clinical diagnosis of chronic AP were obtained during apical surgery procedures, processed by routine technique and histopathologically diagnosed as Apical Granuloma (AG) (n=8) or Radicular Cyst (RC) (n=2) and then, analyzed by immunohistochemistry. The samples were examined with light microscope. As controls, biopsies from healthy periapical ligaments obtained during teeth extraction for orthodontic reasons were used. ResultsCCL-7 was highly expressed in PE samples, and its expression could not be observed in healthy controls. The presence of CCL-7 and CCR-5 in AG and RC is mainly located to the inflammatory infiltrate. No expression was observed in healthy controls. ConclusionsCCL-7 and CCR-5 may play a role in AP pathogenesis, may be by stimulating chemotaxis.

Relationship Between Histological Diagnosis and Evolution of 70 Periapical Lesions at 12 Months, Treated by Periapical Surgery

To relate the histologic diagnosis and radiographic size with the prognosis of 70 biopsies obtained via periapical surgery. Seventy biopsies obtained during periapical surgery were histologically analyzed following curettage of the tissue, establishing the diagnosis as either apical granuloma, radicular cyst, or scar tissue. The radiographic size of the lesion (area in mm(2)) before surgery and after 1 year of follow-up was measured. The evolution at 12 months after surgery was evaluated according to the criteria of von Arx and Kurt. A statistical study was made, the inter-variable relationships were studied using analysis of variance with subsequent Tukey testing and calculation of Pearson correlation coefficient. Results indicated that 65.7% of lesions were granulomas, 25.7% scar tissue, and 8.6% cysts. The larger lesions had the worst prognosis. Cysts had the worst evolution at 12 months after surgery, this result being statistically significant. The prognosis for the periapical lesion depended on the type of lesion and its radiographic size, with cysts and larger lesions having the worst evolution.

Intra-osseous lesions in Greek children and adolescents. A study based on biopsy material over a 26-year period

The purpose of this retrospective study was to investigate the spectrum of oral intra-osseous lesions in a Greek population, consisting of children and adolescents under 18 years of age. Data was obtained from the histopathological reports that accompanied biopsy request forms, which were retrieved from the files of the Oral Pathology Department, Faculty of Dentistry, University of Athens, during a 26-year period. A retrospective analysis with respect to patients' age and gender, frequency and location of the lesions was performed. The lesions were classified into cystic (odontogenic and non-odontogenic) and solid lesions (odontogenic and non-odontogenic). The patients were divided into three age groups: a) 0-6 years old, b) 7-12 years old and c) 13-18 years old. 474 intra-osseous lesions were detected and represented 2.38% out of a total of 19933 biopsies. Male/female ratio was 1.25/1. The majority of the lesions was located in the mandible (49.8%) and occurred in the third age group of patients (58.7%). Odontogenic cysts represented the most frequent intraosseous lesion (64.1%) followed by non-odontogenic solid lesions representing 22.5% of the intra-osseous population. The most frequently encountered lesions in descending order were radicular (36.3%) and dentigerous (18%) cysts, keratocysts (9.5%), apical granulomas (7.6%), odontomas (6%) and fibrous dysplasia (5%). Only 6 malignant lesions were reported (1.3%). This clinicopathologic study revealed that a broad spectrum of mostly benign bony lesions may occur during childhood.

Light microscopic study of periapical lesions associated with asymptomatic apical periodontitis

The purpose of the study has been to evaluate the degree of chronic inflammation in tissues surrounding the apex of the tooth root in patients with apical periodontitis in the remission phase. The material included 37 apical granulomas and radicular cysts obtained as a result of apiectomy, and 20 teeth which were removed together with the focus of the periapical inflammation. Routine histological techniques, as well as the immunofluorescent and immuno-chemical methods were used to examine the material. Despite the absence of clinical symptoms in 23 of 57 cases, the morphological signs of chronic inflammation were observed in the apical area of the tooth root. Morphological signs of viral invasion of epithelial and stromal cells in the radicular cyst wall were revealed in six cases. The presence of the virus of Herpes simplex I in epithelial cells (five cases) and adenoviral invasion (one case) was confirmed by immuno-fluorescent and immuno-chemical methods. Histological examination often reveals morphological signs of an active inflammatory process in the periapical tissues of patients treated during clinical remission. In our opinion, the presence of viruses in the epithelial cells of the radicular cyst may contribute to the persistence of the active stage of the inflammatory process.

ADJUNCTIVE INFRARED DIODE LASER THERAPY ACCELERATES HEALING IN APICAL GRANULOMAS: A CASE REPORT STUDY

The final stage of severe infection round the apex of a tooth is granuloma formation, the treatment of which can be a major problem in clinical dentistry. Although granulomas in the early stages can respond to conservative conventional therapy, such as the application of calcium hydroxide, many in the later stage require surgical intervention with the risk of postoperative sequelae and patient downtime. Low reactive-level laser therapy (LLLT) has been shown to reduce inflammation and accelerate wound healing. The present study was designed to assess the role of 830 nm diode laser therapy in conjunction with conservative conventional therapy in the treatment of severe apical granulomas. Thirty-three young male patients with severe apical granulomas participated in the study, 19 of whom were treated with conventional treatments, and 14 with calcium hydroxide combined with 0.5 J/cm2 - 2 J/cm2 intra- and extraoral diode laser therapy. Significant improvements were seen in the LLLT combination group compared with the control group in the time taken for the resolution of acute postoperative pain (100 vs 500 min) and inflammation (1.6 vs 5.6 days), and long-term tooth remineralization and alveolar bone regeneration (15 vs 33 months). LLLT with the 830 nm diode laser was shown to be safe and effective in combination with conservative conventional therapy in the treatment of severe apical granulomas and was superior to the conventional approach on its own for granulomas of similar severity.

Expression of inducible nitric oxide synthase and heat shock proteins in periapical inflammatory lesions.

The mechanisms responsible for activation and proliferation of lining epithelium involved in inflammatory processes in periapical inflammatory lesions remain unclear. In this study, the expression and distribution of inducible nitric oxide synthase (iNOS) and heat shock proteins (HSPs) were immunohistochemically investigated in periapical inflammatory lesions. Control specimens of periodontal ligaments including Malassez epithelial rests from seven teeth and periapical inflammatory lesions (15 apical granulomas (AGs), 16 radicular cysts (RCs), and 10 residual radicular cysts (RRCs)) were prepared and examined by the standard streptavidin-biotin peroxidase complex method using anti-iNOS rabbit polyclonal antiserum, and anti-HSP27, -HSP60, -HSP70 mouse monoclonal antibodies. Immunoreactivity for iNOS was detected in macrophages, lymphocytes, and endothelial cells of granulation tissue and in lining epithelium of periapical inflammatory lesions. Malassez epithelial rests showed no or slight staining for iNOS. The epithelial staining intensity of iNOS in RCs was greater than that in Malassez epithelial rests and RRCs. Immunoreactivity for HSP27 was recognized in inflammatory cells, endothelial cells and lining epithelium of periapical inflammatory lesions and in Malassez epithelial rests. HSP60 was detected in some lymphocytes of granulation tissue and in lining epithelium of periapical inflammatory lesions, whereas Malassez epithelial rests showed no staining for HSP60. Epithelial HSP60 reactivity was more intense in RCs than in RRCs. HSP70 was expressed in lymphocytes, endothelial cells and lining epithelium of periapical inflammatory lesions and in Malassez epithelial rests. The staining intensity of HSP70 in Malassez epithelial rests was slightly lower than that in lining epithelium of RCs and RRCs. These data demonstrate that the expressions of iNOS, HSP60, and HSP70 are involved in inflammatory processes and might play a role in the activation and proliferation of lining epithelium, leading to progression of periapical inflammatory lesions.

Surgical Removal of a Radicular Odontogenic Cyst in a Four Year Old Dalmatian Dog

A cystic structure was identified radiographically in a four-year-old dog during routine dental prophylaxis. Surgical removal of the cyst lining was achieved by exposure of the site through extraction of the right first to third maxillary incisor teeth (101, 102, 103). The cyst lining was removed en-bloc. The cavity was curetted and filled with decalcified freeze-dried bone. Histological examination revealed a radicular cyst. The proposed etiology is blunt trauma to tooth 103, pulpal necrosis, apical granuloma and resulting cyst formation. Fourteen months following surgery, there was no recurrence of the cyst.

口腔外科領域におけるち密質か粒水酸アパタイト骨補填材の臨床評価 ９施設における協同研究

Several authors reported differences in the tissue response, biocompatibility, stability and osteoconduction of hydroxyapatite (HAP) granules depending on their chemical composition, type (porous or non-porous), shape, solubility behaviour, conditions of production or implant site.Bonetite is one type of non-porous, unabsorbable hydroxyapatite (HAP) granules. We used Bonetite to fill bone defects caused by extraction of erupted teeth (erupted tooth group, 75 cases) or impacted teeth (impacted tooth group, 14 cases) and removal of jaw cysts, apical granulomas or benign tumors (cyst group, 49 cases), and evaluated the usefulness of this material in nine clinics. The following results were obtained:1) Inflammation of the implant site was comparable to general wound healing after the operation.2) No side effects were noted.3) Secondary surgical treatment was done in 4 cases (2.9%), who showed good progress.4) The incidence of wound dehiscence was 9.9%, leakage of HAP granules 27.5% and infection 2. 9% within 1 month after operation. However, the incidence of these findings decreased 3 months after operation, and they were not noted 6 months after operation.5) The mean final retention rate of HAP granules was 84.5% in the erupted tooth group, 92.5% in the impacted tooth group, 90.0% in the cyst group and 86.7% overall.6) As a result, Bonetite was evaluated to be markedly useful or moderately useful in 119 cases (86.2%).7) In conclusion, Bonetite was considered to be one of the most useful implant materials to fill bone defects in the oral and maxillofacial region.

Influence of surgical treatment of periapical lesions on serum and blood levels of inflammatory mediators.

Changes in the serum levels of immunoglobulin IgA, IgG, IgM, positive acute phase proteins and complement activity, as well as the lymphocyte subpopulations and the neutrophil leucocyte-related chemiluminescence in the blood of patients with apical granuloma as related to endodontic and surgical treatment were investigated. Measurements were performed on admission, and 7 days and 3 months after the treatment. Elevated IgM concentration, positive acute-phase protein levels and spontaneous whole-blood chemiluminescence were noted at admission. However, a significant decrease in the serum level of each of the six investigated acute-phase proteins, and in the spontaneous chemiluminescence of blood was observed during the 3-month follow-up period. The significant increase in serum complement activity following therapy suggests that complement fixation might have occurred in these patients. A significant increase in the ratio of early sheep erythrocyte rosette-forming lymphocytes was also observed. The results of this study provide evidence for complete recovery after elimination of local inflammation by proper endodontic treatment and apicectomy in patients with apical granuloma.

Recent development in endodontic research.

In essence, endodontics as a clinical discipline is concerned with the prevention and treatment of pulpal and periapical infection. In recent research the infective process has been investigated as well as the mechanisms by which the pulp and periodontium deal with microbial insults. With regard to the pulp, findings on the hemodynamics of pulpitis suggest that the inflammatory response in this tissue is much less influenced by the special anatomic environment of the tooth than was previously believed. Pulpal diseases are being underdiagnosed, mostly because of inadequate examination methods. Laser Doppler flowmetry which gives a vascular rather than a nervous response may gain importance in pulpal diagnostics in the future. It is established that apical periodontitis with bone resorption cannot develop in the absence of bacteria in the root canal system. Root canal infection is characterized by a wide variety of combinations of relatively few anaerobic bacteria, and bacterial synergism plays an important role in maintaining the infection. Microbial invasion of an apical granuloma may take place. Non-oral and environmental organisms like Pseudomonas aeruginosa are frequently isolated from treatment-resistant cases. Success of endodontic treatment depends on the reduction or elimination of the infecting bacteria. This may predictably be obtained after a thorough chemo-mechanical instrumentation and disinfection of the root canal with calcium hydroxide. The standardized technique which entails the preparation of a cylindrical apical box with removal of significant amounts of dentin near the root apex predictably gives a clean canal. This technique has provided excellent clinical and radiographic results in well documented follow-up studies.