Deposition vs. Root Canal

Several irrigating solutions have been considered in order to decrease endodontic infection and contribute to canal disinfection, including: However, up to now, sodium hypochlorite and chlorhexidine are the most often indicated antimicrobial agents for treatment protocols against endodontic and periodontal infections 24 , 25 , The antimicrobial effect of sodium hypochlorite by direct contact with E. The positive culture of microorganisms following the application of the irrigating solutions ozonated water, gaseous ozone, 2. Thus, when a medicament does not reach the target microorganism, its killing potential cannot be recognized.

Therefore, it cannot be stated whether the microbial strains were resistant to one or other medication. In this case, it is likely that the microorganisms were able to survive, adapt and tolerate the critical ecological conditions. In the same direction, the properties of calcium hydroxide stem from its dissociation into calcium and hydroxyl ions and the action of these ions on tissues and bacteria explains biological and antimicrobial properties of this substance Thus, it was shown that calcium hydroxide induces the deposition of a hard tissue bridge on pulpal and periodontal connective tissue 41 - Its action on connective tissue pulpal and periodontal tissues revealed the ability to stimulate mineralization, from the significant involvement of alkaline phosphatase and fibronectin 39 - There is a great release of hydroxyl ions from calcium hydroxide, which are able of altering the integrity of the bacterial cytoplasmic membrane through the toxic effects generated during the transfer of nutrients or by the destruction of the phospholipids of unsaturated fatty acids.

The influence of pH alters the integrity of the cytoplasmic membrane by biochemical injury to organic components proteins, phospholipids and transport of nutrients. The maintenance of a high concentration of hydroxyl ions can change the enzymatic activity and provide its inactivation In addition, the healing process in teeth with AP after RCT in two appointments with the use of calcium hydroxide paste showed a better status of periapical tissue with mineralized barrier 43 - The presence of biofilm in the root canal system is a challenge to the outcome of RCT 26 , The active participation of mechanical action of endodontic instruments combined with antimicrobial strategies appears to be crucial for decreasing root canal infection.

The estimation of the RCT prognosis must be related to criteria for understanding the success. This aspect implies in evaluating results based on longitudinal monitoring, which requires a standard. The RCT success criteria and its prevalence should be routinely reevaluated. AP is a consequence of root canal system infection, which can involve progressive stages of inflammation and changes of periapical bone structure, resulting in resorptions identified as radiolucencies in radiographs RCT failures may involve microbial and non-microbial factors, as discussed previously 9 - 12 , A high rate of failure is associated with endodontically treated teeth associated with AP, overfilling, and teeth that were not properly restored after RCT 18 - 22 , 27 , 47 - Thus, utmost care must be taken to establish criteria to define success.

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On this account, the life of a tooth endodontic treatment may be rely on the time and the age of the individual. In a prospective analysis, an endodontically treated tooth is expected to remain throughout the individual's life. It is important to recognize that along people's life, some diseases may develop and impact their health. Incidentally, an infection or re-infection may arise some time after RCT. To characterize the outcomes of endodontically treated teeth with vital pulp healthy or inflamed pulp , infected pulp, AP and periapical abscess, must be considered the time since RCT conclusion and the definite restoration.

The previous status of pulp and periapical tissue may aid in the interpretation of actual clinical conditions. Strindberg 50 described important clinical and radiographic factors associated with RCT success and failure. A considerable number of clinical studies have discussed the causes of failure of endodontically treated teeth and prospects for prognosis in retreatment 50 - The correlation of RCT failure with infected root canal was evident in several conditions 1 , 3 , 8 - 20 , 24 - 27 , 35 - 40 , 47 - Traditionally, three aspects are associated in the analysis of RCT success — the clinical, radiographic and microscopic characteristics.

In the clinical context, two of these aspects normally guide the decision-making process: The cases of doubt on the success or failure involve a transition phase and definition of criteria may be imposed by the limitations of the used clinical or imaging exams. Clinical success and clinical silence are different aspects to be analyzed. Clinical failure may present or not a symptomatic pain condition.

In this sense, AP cannot be correctly identified by periapical radiography only. The experienced professional has many resources to identify the agent responsible for the failure. Notwithstanding the dentist's skills, the diagnosis of odontogenic pain should always follow an accurate protocol, since the pain felt by the patient may not have a direct association with a well or bad endodontically treated tooth. Various factors may affect tooth survival, such as dental caries, periodontal disease and RCT.

The prevalence of endodontically treated teeth associated or not with AP has been examined in several populations 1 , 48 , 49 , 61 , 72 , Regarding the prevalence of endodontically treated teeth in Brazilian adults, a previous study showed that in a sample of 29, teeth, only 6, RCT was most frequent in maxillary premolars and molars, whereas mandibular incisors showed the lowest prevalence. Most endodontically treated teeth were found in people aged 46 to 60 years A total of 1, periapical radiographs of endodontically treated teeth by postgraduate students were evaluated 1.

AP prevalence was significantly higher in teeth with poor endodontic treatment Prevalence of AP was also higher in teeth with poor coronal restoration Based on periapical radiographs, the prevalence of AP was low when associated with a high technical quality of RCT. In health sciences, such as endodontics, various advances were applied to clinical practice.

The therapeutic assessment of dental treatment by computed tomography characterizes a sensible advance of information in health 76 , This contribution may be applied to planning, diagnosis, therapeutic process and prognosis of several diseases. The continuous advance of technology enabled the development of cone beam computed tomography CBCT 78 , 79 , which has widen numerous perspectives for application in different research areas and clinical dentistry 80 - Imaging resources have been routinely used before, during and after dental treatment.

Conventional radiographic images provide a two-dimensional rendition of a three-dimensional structure, which may lead to interpretation errors. Periapical lesions of endodontic origin may be present but not visible on conventional 2D radiographs 80 - The accuracy of diagnosis is a critical factor for the success. The correct management of CBCT images may reveal abnormalities unable to be detected in periapical radiography and may enhance a more predictable planning and treatment 80 - The possibility of a map-reading approach with CBCT images reduces the problems related to difficult evaluation conditions that require special care during diagnosis In view of the limitations of periapical radiography to visualize AP, a review of epidemiologic studies should be undertaken considering the quality of periapical aspects provided by CBCT images.

It will certainly reduce the influence of radiographic interpretation, with less possibility for false-negative diagnoses. AP prevalence in endodontically treated teeth, when comparing the panoramic and periapical radiographs and CBCT images, was A considerable discrepancy can be observed among the imaging methods used to identify AP. AP was correctly identified in Minor changes in sensitivity were found for different teeth groups, except for incisors in panoramic radiographs. ROC analysis suggests that AP is correctly identified with conventional methods in an advanced stage.

In teeth where the small size of the existing radiolucency was diagnosed by radiographs and considered to represent periapical healing, enlargement of the lesion was frequently confirmed by CBCT. In clinical studies, two additional factors may have further contributed to the overestimation of successful outcomes after root canal treatment: The outcomes of root canal treatment should be re-evaluated in long-term longitudinal studies using CBCT and stricter evaluation criteria.

Characteristics of the clinical and imaging outcomes from RCT include: In case of doubt, it is essential to discuss the clinical case with a more experienced professional, as in some cases it is not easy to determine the differential diagnosis of diseases of non-endodontic and endodontic origin. Various radiolucent images may be associated with the apex, without being diseases of microbial origin and could be misinterpreted as AP 5 - 7. The time to start the treatment is also a key factor to determine success or failure.

The possibility of map-reading in CBCT images minimizes several problems related to complex diagnosis, particularly in dubious cases. A strategy to minimize metallic artifact in root perforation associated with intracanal post is to obtain sequential axial slices of each root, with an image navigation protocol from coronal to apical or from apical to coronal , with 0. This map reading provides valuable information showing dynamic visualization toward the point of communication between the root canals and the periodontal space, associated with radiolucent areas, suggesting root perforation.

Determination of Working Length of Root Canal

Operative procedural errors OPE may occur and they represent risk factors able to compromise a tooth 86 , Errors characterize disability, non-observance of therapeutic protocol and low level of knowledge involving the endodontic principles. Deficient attendance may be responsible for severe consequences and sequels, which impairs the prognosis, and may result in serious judicial questions In endodontically treated teeth, OPE included underfilling, overfilling, and root perforation; OPE in dental implants were thread exposures, contact with anatomical structures, and contact with adjacent teeth.

Underfilling, overfilling, and root perforations were detected in Dental implants with thread exposures, contact with important anatomical structures and contact with adjacent teeth were seen in OPE were detected in endodontically treated teeth and dental implants, and underfilling and thread exposures were the most frequent occurrences, respectively. The extension of treatment in a tooth with indication for extraction can be a dental implant. The problem of replacing a biological structure by biocompatible materials requires care and precise indication.

Information about criteria and rates of success in endodontically treated teeth and dental implants are of utmost importance. It appears that few high-level studies have been published in the past four decades related to the success and failure of nonsurgical root canal therapy. The data generated by this search can be used in future studies to specifically answer questions and test hypotheses relevant to the outcome of nonsurgical root canal treatment.

The current moment of endodontic science is promising in view of all the knowledge acquired over the last few years New technologies such as CBCT influenced the quality of diagnosis, planning, therapy and longitudinal control. A wide array of endodontic instruments for safer root canal preparation was introduced in endodontics. Some of these advances contributed to the revision of concepts, and to determine adjustments to the treatment protocol. One concern discussed at meetings in endodontics and in several recent studies 80 - 86 relates to overestimated numbers of success in RCT.

Depending on the dentist's knowledge and skills for interpreting CBCT images, higher percentages of errors and failures in RCT may be identified. The possibility of map-reading on the CBCT scans can characterize the reality of a multidimensional structure, aiding with precise information the presence, absence or regression of AP. The life of an endodontically treated tooth implies understanding the biological and mechanical results as a multifactorial event, over the life span of the individual.

The authors deny any conflicts of interest related to this study. Prevalence and risk factors of apical periodontitis in endodontically treated teeth in a selected population of Brazilian adults. Braz Dent J ; Renouard F, Charrier J-G. A la recherche du maillon faible: Diagnostic and clinical factors associated with pulpal and periapical pain. Factors affecting the outcome of orthograde root canal therapy in a general dentistry hospital practice. Mesenchymal chondrosarcoma mimicking apical periodontitis. Ameloblastoma suggesting large apical periodontitis.

Intraosseous lipoma in the periapical region of a maxillary third molar. Biology and pathology of apical periodontitis. Estrela C, Bueno MR. Epidemiology and therapy of apical periodontitis. Foreign body reaction maintaining post-treatment apical periodontitis. Periapical cysts sustain post-treatment apical periodontitis.

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Persistent periapical radiolucencies of root filled human teeth, failed endodontic treatments and periapical scars. Sundqvist G, Figdor D. Life as an endodontic pathogen: Ecological differences between the untreated and root-filled root canals. Clinical significance of dental root canal microflora. On the causes of persistent apical periodontitis: Int Endod J ; An introduction to cellular microbiology. Cambridge University Press, The frequency, technical standard and results of endodontic therapy.

University of Bergen PhD Thesis , Retreatment of endodontic fillings. Scand J Dent Res ; Influence of apical overinstrumentation and overfilling on re-treated root canals. Root canal treatment with calcium hydroxide I: Root canal treatment with calcium hydroxide II: Materials used for root canal obturation: Antimicrobial efficacy of ozonated water, gaseous ozone, sodium hypochlorite and chlorhexidine in infected human root canals. Control of microorganisms in vitro by endodontic irrigants.

Introduction

Antibacterial efficacy of intracanal medicaments on bacterial biofilm: J Appl Oral Sci ; Influence of length of root canal obturation on apical periodontitis detected by periapical radiography and cone beam computed tomography. The cemento-dentino-canal junction, the apical foramen, and the apical constriction: Apical terminus location of root canal treatment procedures. Apical limit of root canal instrumentation and obturation, part 1: Ricucci D, Langeland K. Apical limit of root canal instrumentation and obturation, part 2: Success rate of endodontic treatment of teeth with vital and nonvital pulps: Determining the optimal obturation length: Prevalence and extent of long oval shape of canals in the apical third.

Influence of cervical preflaring on apical file size determination. Changes in root canal geometry after preparation assessed by high-resolution computed tomography. Prevalence of Enterococcus faecalis at multiple oral sites in endodontic patients using culture and PCR. Mechanism of action of calcium and hydroxyl ions of calcium hydroxide on tissue and bacteria.

Braz Dent J ;6: Mechanism of action of sodium hypochlorite. Histochemical response of amputed pulps to calcium hydroxide. Rev Bras Pesq Med Biol ;4: Holland R, Souza V. Ability of a new calcium hydroxide root canal filling material to induce hard tissue formation. A comparison of one versus two appointment endodontic therapy in dogs' teeth with apical periodontitis. Estrela C, Holland R. Mizuno M, Banzai Y. Calcium ion release from calcium hydroxide stimulated fibronectin gene expression in dental pulp cells and the differentiation of dental pulp cells to mineralized tissue forming cells by fibronectin.

Microbiologic analysis of teeth with failed endodontic treatment and the outcome of conservative re-treatment.

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Ray HA, Trope M. Working length is defined in the endodontic glossary as the distance from a coronal reference point to the point at which canal preparation and obturation should terminate. According to Kuttler , the narrowest diameter of the canal is definitely not at the site of exit of the canal from the tooth but usually occurs within the dentin, just prior to the initial layers of cementum. According to Ricucci and Langeland, the apical constriction is the narrowest part of the canal with the smallest diameter of blood supply, thus creating the smallest wound site and best healing condition [ 1 ].

This anatomical landmark can be called the minor diameter of the canal. However, the cemento-dentinal junction CDJ and apical constriction do not always coincide, particularly in senile teeth as a result of cementum deposition, which alters the position of the minor diameter [ 2 ]. The minor diameter represents the transition between the pulpal and the periodontal tissue, located in the range of 0. A working length established beyond the minor diameter may cause apical perforation and overfilling of the root canal system. This may increase postoperative pain and delay or prevent healing.

Alternately, a working length established short of the minor diameter may lead to inadequate debridement and underfilling of the canal. Retained pulp tissue may persist and cause prolonged pain. In addition, microleakage into the canal space may result in impaired healing [ 4 ]. The generally accepted method of working length determination is the radiographic method but the apical constriction cannot be accurately determined radiographically.

The electronic apex locator has attracted a great deal of attention as it operates on the basis of electronic principles rather than by a visual inspection. The electronic apex locator is one of the breakthroughs that brought electronic science into the traditionally endodontic practice [ 5 ].

Electronic apex locators are particularly useful when the apical portion of the canal is obscured by anatomic structures, such as impacted teeth, tori, the zygomatic arch, excessive bone density, overlapping roots or shallow palatal vaults. Electronic apex locators currently are being used to determine the working length and as an important adjunct to radiographs.

Electronic apex locators reduce the radiation dose and treatment time. The earlier apex locators were based on the principle of resistance and impedance type. The newly developed apex locators are based on the impedance of a given circuit that is substantially influenced by the frequency of the current flow. These devices are called frequency dependent apex locators [ 6 ].

These apex locators are based on the principle that there is a maximum difference of impedance between electrodes depending on the frequencies used. The major advantages with these apex locators are that they operate in an electroconductive environment in the presence of pus and pulpal tissue remnants. A total of teeth in the same or different patients that were asymptomatic and without any periapical infection were identified. An access cavity was prepared and the pulpal contents were removed from the pulp chamber as well as the canals.

A root canal file was selected corresponding to the canal size and inserted in the canal. Care was taken that the tooth was extracted in one piece without fracture of the root, although there were 11 fractures of roots in the study. These 11 cases were removed from the study group and fresh cases were incorporated to complete the sample size. Care was also taken that the file stabilized in the root canal was not disturbed. After extraction the tooth was placed in hydrogen peroxide for two minutes and washed under flowing water.

A window was cut on one surface of the root apex approximately four mm from the apex to expose the root canal. It may also be clarified here that while taking radiographs, long cone technique was used rather than the short cone, as the latter leads to elongation of the image and more discrepancy. In six cases the apical opening was 1—2 mm short of the apical tip of the root. Since this would have affected the result because the radiographic measurements were made from the radiographic tip of the root, these six cases were not considered in the study.

It may be reiterated here that only those cases were considered where the apical foramen coincided with the apical tip of the root. The purpose of the present study was to compare the accuracy of frequency based apex locator Root ZX and conventional radiographic method under clinical conditions. The accuracy of the apex locator was compared using single canal single rooted teeth incisor, canine and lower premolar teeth that were to be extracted for periodontal or orthodontic reasons.

Determination of Working Length of Root Canal

It was thus concluded that the electronic method is a more accurate method as compared to radiographic method for determination of working length of the root canal. Most experts agree that the canal preparation should terminate at the CDJ. Clinically this is not practical. In the early days of endodontics, when radiographs were not being used in dentistry, working length was approximated to where the patient experienced pain.

This obviously led to multiple errors. If vital tissues were left in the canal, the calculation would be too short. If a periapical lesion were present, the calculation would be long. Radiographs in dentistry came about in However, the thought at that time was that the dental pulp extended through the tooth, past the apical foramen, into the periapical tissue and that the narrowest portion of the tooth was at the extreme apex.

The radiographic apex was thought to be the correct site to terminate the canal preparation. In the 's, Blaney and Coolidge offered information that indicated that filling slightly short of the root tip gave the best results. In , Kuttler gave the most comprehensive anatomic microscopic study of the root tip. He studied several thousand teeth. Not everyone embraced his ideas initially but over the past 40 years his ideas are still practiced.

In individuals between the age group of 18—25 years, the average distance between the minor and major diameters was 0. In older individuals the average distance was 0.

Therefore Kuttler felt that it was an unwise clinical procedure to fill to the radiographic apex because it caused postoperative pain and lowered the success rate. Many studies have followed and supported Kuttler's findings. In , Ingle used the pre-treatment radiograph in a mathematical procedure for determining working length. The original tooth image was measured on the pretreatment radiograph, following substraction of a standard 2—3 mm from that length to compensate for distortion.

There are several ways to determine the working length of the root canal viz radiographs, electronic apex locators, tactile sense, patient response, knowledge and experience, predetermined normal tooth length, use of paper points, mathematical equations etc. Accuracy in length determination is necessary to avoid damage to the apices of teeth and to the periapical tissues during instrumentation, thus providing better conditions for healing after endodontic treatment.

As with anything that is open to interpretation, variation exists in the radiographic determination of endodontic file length. The advantage of apex locators are that they are supposedly accurate, easy, fast and reduce exposure to radiation. Artificial perforation can be recognized and it is the only method that can measure length to the apical foramen and not the radiographic apex.

The disadvantages are that it requires a special device and accuracy is influenced by electrical condition of canal. Most of the disadvantages come from the fact that the magnitude of the impedance of the canal is influenced by the electrolytes present inside the canal.

Electronic apex locators have limitations in teeth with wide open apex.