Thermal injury through intraradicular heat transfer using ultrasonic devices

Management of an Intracanal Separated Instrument in the Lower Right First Molar: A Case Report

Separating an endodontic instrument is one of the most frequent errors during a root canal treatment. If endodontic instruments get separated, it could hinder disinfection and prevent access to the apical portion of the root. It compromises the success of the treatment by impeding the proper debris removal from the canal. But now that techniques and tools have advanced, it is feasible to remove a separated instrument from the root canal successfully. This case report presents the management of a separated instrument, demonstrating the successful removal of the separated instrument.

Comparative evaluation of increase in temperature on the external root surface of teeth during retrieval of broken NiTi instrument using two ultrasonic tips and two power settings: An in vitro study

Context

An unfavorable event that can hinder endodontic treatment and affect the outcome of root canal treatment is the separation of endodontic instruments. Endodontic instrument separation can occur due to clinical or metallurgical factors. Friction between the ultrasonic tip and the remaining dentin generates heat, which is subsequently transferred to the external root surface. Elevated temperatures exceeding 10°C above body temperature for more than a minute may result in injury to periodontal or bone tissue.

Aim

The aim of this study was to evaluate and compare temperature rise on the external root surface of teeth during retrieval of broken NiTi instrument using two different ultrasonic tips and two power settings.

Materials and Methods

In each group, a sample size of 8 was sufficient to attain a statistical power exceeding 90%, enabling the detection of a minimum mean difference of 0.9204 (delta) through a one-way ANOVA test at a 95% confidence level (alpha 0.05). After access opening and working length determination, samples were randomly distributed into two groups - Group 1 (A and B) - ProUltra tip at high and low power settings and Group 2 (A and B) - Cric Dental IR3 at high and low power settings. The temperature rise was measured using K-type thermocouple thermometer. The comparisons were analyzed using the Kruskal-Wallis test with pairwise comparisons using the Dunn's test.

Results

Group 1A and Group 1B resulted in lower heat generation compared to Group 2A and 2B and its difference was statistically significant (P < 0.05). Minimum temperature rise is seen in the ProUltra group at lower power settings (Group 1A) at the apical level and maximum temperature rise is seen in the Cric Dental IR3 group at higher power settings (Group 2B) at the middle third level.

Conclusion

It was found that there is a significant temperature rise seen when ultrasonic tips are used for the retrieval of separated files, especially at higher power settings. The ProUltra tip demonstrated the lowest temperature rise at lower power settings, particularly at the apical level, whereas the IR3 Cric Dental tip exhibited the highest temperature rise, notably at higher power settings and the middle third level.

Endodontic Orthograde Retreatments: Challenges and Solutions

Endodontic orthograde retreatments are considered one of the possible treatment options in case of post-treatment diseases considering the promising results present in the literature. Despite this, a plethora of articles have been published on this topic, and drawing conclusions could be challenging. For this reason, this review aims to summarize the crucial points on each aspect of non-surgical endodontic retreatments, discussing and comparing the current protocols, techniques, materials, and indications. Taking into consideration data from the literature, in terms of diagnosis, CBCT should be considered the first choice, since it can thoroughly affect the diagnosis and treatment plan. Regarding the procedural phases, some conclusions can be drawn: when present, coronal restoration materials such as crowns, partial prostheses, post, and core should be removed; the use of magnification devices, ultrasonic instruments, and an in-depth interpretation of radiographic images with both 2D and 3D images are strongly recommended during the orifice location; additional protocols such as irrigants activation, ultrasonic cleaning, and rotary or reciprocating instrumentation of treated canals are strongly recommended for filling materials removal and to achieve a high-quality chemo-mechanical disinfection; perforations should be treated as soon as possible, and the material of choice to treat them is the MTA or other calcium-silicate-based repair materials; the presence of ledges does not intrinsically reduce the success rate of RCRts if properly managed; in case of instrument fragments, their removal should be considered as the first treatment option, however many variables should be considered to select the proper technique or consider the option of bypassing.

Assessment of the root surface temperature during the use of intracanal agitation systems: In vitro study

This study aimed to evaluate the temperature changes that the different methods of agitation of irrigants promote on the external dental root surface. Nine extracted human lower premolars were standardized by cone-beam computed tomography and used. The root canal was instrumented with a Reciproc 40.06 file. Temperature measurement was performed using K-type thermocouple sensors attached to the middle, cervical, and apical thirds of the teeth. The teeth had their roots immersed in distilled water at 37ºC, which were distributed into 3 experimental groups according to the mechanical agitation methods to be studied. US Group (n=3), Irrisonic Ultrasonic Tip activated through ultrasound; EC Group (n=3), Easyclean Tip coupled to a contra-angle low-speed handpiece; XP Group (n=3), XP-endo Finisher file coupled to an endodontic electrical motor. Temperature measurements were performed simultaneously with agitation and irrigation of intracanal irrigants. Statistical analysis was performed using SPSS software with a significance level of 5%. For multiple comparisons, the Tukey test was used. The association between mechanical agitation methods and root third was statistically significant. Regarding the temperatures recorded on the external surface of the roots, the ultrasonic tip was significantly higher than the XP-endo Finisher file and the Easyclean tip, which did not differ from each other. Regarding the ultrasonic tip, the external temperature in the middle third (39.46ºC) of the root was significantly lower than in the cervical (40.41ºC) and apical third (40.53ºC). None of the agitation methods of irrigants studied presented heating above 47ºC, and their use is safe for periodontal tissues.

Guided Endodontics in the Management of Intracanal Separated Instruments: A Case Report

AIM

The aim of this case report is to describe the removal of a fractured file in mandibular right first premolar through the application of an endodontic template to guide a trephine until the file.

BACKGROUND

The fracture of an endodontic instrument is a rare complication that requires therapeutic management. Removal procedures often cause excessive dentine loss. To limit this inconvenience, several techniques describing the removal of fractured files in the coronal third of the canal have been proposed. The guide facilitates the use of the Zumax removal kit (Zumax Medical Co. Ltd., Suzhou, China).

CASE DESCRIPTION

A 30-year-old patient was referred to dental office for the endodontic retreatment of his mandibular right first premolar. The tooth was painful to percussion and buccal palpation. The periapical radiograph showed a periapical lesion, a defective root canal treatment, and the presence of a fractured file. It was decided to use the Zumax kit in order to remove the instrument. By using digital implantology software, a guide was constructed with a tube to guide a trephine and achieve straight-line access. The trephine was later driven by the resin guide. After completing the drilling, the instrument was removed with the Zumax extractor and the canal was then prepared, disinfected, and filled.

CONCLUSION

The current case describes the removal of a separated instrument by use of a new approach that is planned on computer software and guided by a resin guide.

CLINICAL SIGNIFICANCE

The guided endodontic technique avoids excessive loss of dental structure and simplifies the procedure by reducing chair time and increasing the operator's confidence.

Patient safety in dental care: an integrative review

Adverse events pose a serious problem for quality of healthcare. Dental practice is eminently invasive and involves close and routine contact with secretions; as such, it is potentially prone to the occurrence of adverse events. Various patient safety studies have been developed in the last two decades, but mostly in the hospital setting due to the organizational complexity, severity of the cases, and diversity and specificity of the procedures. The objective was to identify and explore studies on patient safety in Dentistry. An integrative literature review was performed in MEDLINE via PubMed, Scopus via Portal Capes, and the Regional Portal of the Virtual Health Library, using the terms patient safety and dentistry in English, Spanish, and Portuguese, starting in 2000. The research cycle in patient safety was used, as proposed by the World Health Organization to classify studies. We analyzed 91 articles. The most common adverse events were allergies, infections, diagnostic delay or failure, and technical error. Measures to mitigate the problem highlight the need to improve communications, encourage reporting, and search for tools to assist the management of care. The authors found a lack of studies on implementation and assessment of the impact of proposals for improvement. Dentistry has made progress in patient safety but still needs to transpose the results into practice, where efforts are crucial to prevent adverse events.

Broken File Retrieval in the Lower Right First Molar Using an Ultrasonic Instrument and Endodontic Micro Forceps

Broken files affect cleaning, shaping, and filling processes of the root canal, thereby causing maintenance failure. Objective. This report explains how to remove broken files using ultrasonic instruments and endodontic micro forceps. Case Report. A 25-year-old female patient had incomplete root canal treatment at the lower right first molar 1 week ago. There were radiolucency in the bifurcation and apical root and the presence of broken files in the 1/3 coronal mesiolingual root. The retrieval started by making a staging platform with an ET20 ultrasonic tip. Endodontic micro forceps were used including a screw wedge that works by clamping the file fragments through a mechanical lock and pulling them to the coronal. Conclusion. It is possible to successfully remove broken files from the root canal using ultrasonic instruments and endodontic micro forceps.

Separated Instrument in Endodontics: Frequency, Treatment and Prognosis

Instrument separation during endodontic therapy is a frequent accident with rotary instruments being more likely to separate than manual ones. The treatment of cases with a separated instrument can be either conservative or surgical. A conservative approach involves the following treatment choices: a) bypass of the fragment, b) removal of the fragment, c) instrumentation and obturation coronally to the fragment. Concerning the removal of a separated instrument, a variety of techniques and systems have been developed. Ultrasonics, in combination with the operative microscope constitute the most effective and reliable tools for removing a separated endodontic instrument from a root canal. The likelihood of successful removal depends on: the level of separation (coronal, middle or apical third); location in relation to the root canal curvature; the type of separated instrument; its length; the degree of canal curvature and the tooth type. Several complications may occur during the management of a separated instrument: separation of the ultrasonic tip or file used for bypassing or removing the instrument; further separation of the fragment; perforation; ledge; extrusion of the file into periapical tissues; tooth weakening due to dentin removal, as well as excessive temperature rise in periodontal tissues. Prognosis for a tooth retaining a separated instrument depends on the presence of a periapical lesion, the microbial load of the root canal during the time of separation and the quality of the obturation.

Restoration of the root canal treated tooth

When considering endodontically treated teeth, the quality of the restoration is important from the outset. It sheds light into possible causes of pulp necrosis or failure of endodontic treatment and influences the outcome of future endodontic treatment. A tooth undergoing endodontic treatment requires an effective coronal seal during and following completion of endodontic treatment. This paper discusses, using the available literature, the maintenance of optimal coronal seal and coronal integrity during and after root canal treatment.

Coverage of denuded labial bone resulting from post space preparation with a free gingival autograft: lessons learnt

Rehabilitation of endodontically treated teeth by post and core preparation is a common procedure in day to day dental practice. However, in some instances, post space preparation can produce excessive frictional heat leading to significant damage to the attachment apparatus of the tooth as well as to the overlying soft tissue. This report describes a case of mucosal dehiscence arising due to trauma induced by inadvertent post space preparation. The denuded mucosa was restored to its physiological position with the help of free gingival autograft obtained from the palatal donor site. The aesthetic results obtained were excellent and have been stable for a period of 2 years.

Clinical decision-making after endodontic instrument fracture

When a file fractures during root canal treatment there are several treatment options available to the clinician. The definitive management should be based on a thorough knowledge of the success rates of each treatment option, balanced against potential risks of removal or file retention. Although integration of modern techniques into endodontic practice has improved the clinician's ability to remove fractured files, removal may not always be possible or even desirable. The aim of the third and final review in this series was to analyse the literature with regard to the management of fractured files. Analysis of the literature demonstrated that the presence of a fractured instrument need not reduce the prognosis if the case is well treated and there is no evidence of apical disease. Therefore, in cases without apical disease removal of the file may not be necessary and retention or bypass should be considered. If apical disease is present, file fracture significantly reduces prognosis indicating a greater need to attempt file removal or bypass. A plethora of different methods have been employed to remove fractured instruments and although successful, these techniques usually require the use of the operating microscope and specialist care. Removal of a fractured file is not without considerable risk, particularly in the apical regions of the root canal, therefore, leaving the fragment in situ should be considered if referral is not possible. Finally, it is imperative that the patient is informed (accompanied by appropriate record keeping) if instrument fracture occurs during treatment or if a fractured file is discovered during a routine radiographic examination.

Temperature rise during experimental light-activated bleaching

The purpose of this study was to evaluate the surface and intrapulpal temperatures after treatments with different bleaching gels subjected to different types of light activation. A K-type thermocouple and infrared thermometer were used to measure the temperature increase during the 15- or 30-min treatment period. Light-emitting diode with a center wavelength of 405 nm (LED405), organic light-emitting diode (OLED), and femtosecond laser were tested and compared to ZOOM2. The tooth surface was treated with five bleaching agents and Vaseline which served as a control.The generalized estimating equation (GEE) model was applied for testing the differences in temperature increase. The ZOOM2 light source led to the largest increase in mean pulpal and tooth surface temperatures of 21.1 and 22.8 °C, followed by focused femtosecond laser which increased the pulpal and surface temperatures by up to 15.7 and 16.8 °C. Treatments with unfocused femtosecond laser, LED405, and OLED induced significantly lower mean temperature increases (p < 0.001 for each comparison with ZOOM2 and focused femtosecond laser), both in the pulp chamber (up to 2.7, 2.5, and 1.4 °C) and at the tooth surface (up to 3.2, 3.4, and 1.8 °C). Significant differences between pulp chamber and tooth surface measurements were obtained for all types of bleaching gel, during treatments with ZOOM2 (p < 0.001), LED405 (p < 0.001), and unfocused (p < 0.001) and focused femtosecond laser (p ≤ 0.002). Different bleaching agents or Vaseline can serve as an isolating layer. Focused femtosecond laser and ZOOM2 produced large temperature increases in the pulp chamber and at the tooth surface. Caution is advised when using these types of light activation, while LED405, OLED, and unfocused femtosecond laser could be safely used.

Management of intracanal separated instruments

INTRODUCTION

Intracanal separation of endodontic instruments may hinder cleaning and shaping procedures within the root canal system, with a potential impact on the outcome of treatment. The purposes of this narrative review of separated instruments were to (1) review the literature regarding treatment options, influencing factors, and complications and (2) suggest a decision-making process for their management.

METHODS

An online search was conducted in peer-review journals listed in PubMed to retrieve clinical and experimental studies, case reports, and review articles by using the following key words: instruments, files, obstructions, fractured, separated, broken, removal, retrieval, management, bypassing, and complications with or without root canal and endodontic.

RESULTS

There is a lack of high-level evidence on management of separated instruments. Conventional conservative management includes removal of or bypassing the fragment or filling the root canal system to the coronal level of the fragment. A surgical intervention remains an alternative approach. These approaches are influenced by a number of factors and may be associated with complications. On the basis of current clinical evidence, a decision-making process for management is suggested.

CONCLUSIONS

Guidelines for management of intracanal separated instruments have not been formulated. Decisions on management should consider the following: (1) the constraints of the root canal accommodating the fragment, (2) the stage of root canal preparation at which the instrument separated, (3) the expertise of the clinician, (4) the armamentaria available, (5) the potential complications of the treatment approach adopted, and (6) the strategic importance of the tooth involved and the presence/or absence of periapical pathosis. Clinical experience and understanding of these influencing factors as well as the ability to make a balanced decision are essential.

Thermal irritation of teeth during dental treatment procedures

While it is reasonably well known that certain dental procedures increase the temperature of the tooth's surface, of greater interest is their potential damaging effect on the pulp and tooth-supporting tissues. Previous studies have investigated the responses of the pulp, periodontal ligament, and alveolar bone to thermal irritation and the temperature at which thermal damage is initiated. There are also many in vitro studies that have measured the temperature increase of the pulp and tooth-supporting tissues during restorative and endodontic procedures. This review article provides an overview of studies measuring temperature increases in tooth structures during several restorative and endodontic procedures, and proposes clinical guidelines for reducing potential thermal hazards to the pulp and supporting tissues.

Infrared thermographic comparison of temperature increases on the root surface during dowel space preparations using circular versus oval fiber dowel systems

PURPOSE

The purpose was to evaluate temperature increases during dowel space preparations with oval and circular fiber dowel systems.

MATERIALS AND METHODS

This study included 42 single-rooted human mandibular premolars. Roots were scanned with cone-beam computerized tomography (CBCT) to determine the ovoid root canal morphology. Root canals were treated with Ni-Ti rotary instruments and obturated. A second CBCT was taken to determine the thinnest dentin thickness of each root. Roots were randomly divided into two groups (n = 21) according to the fiber dowel system used: group 1, circular fiber dowel system (D.T. Light-Post); group 2, oval fiber dowel system (Ellipson Post). Dowel spaces were prepared using a circular fiber dowel drill and a diamond-coated ultrasonic tip with an oval section under water cooling until 9 mm dowel spaces were obtained. Temperature changes were recorded from the thinnest root surfaces using a FLIR E60 thermal imaging camera.

RESULTS

Temperature increases were significantly greater with the circular fiber dowel system than with the oval fiber dowel system (p < 0.05).

CONCLUSIONS

Although both dowel systems generated high temperature increases on root surfaces, the relatively lower temperature increase associated with the use of oval fiber dowels in ovoid canals makes it preferable to the use of circular fiber dowels.

Effect of different water flows on root surface temperature during ultrasonic removal of posts

OBJECTIVE

This in vitro study evaluated rises in temperature on the outer root surface of human incisors during ultrasonic post removal with different water flows.

STUDY DESIGN

Thirty-six extracted teeth (12 maxillary central incisors, 12 maxillary lateral incisors, and 12 mandibular incisors) were used. After root canal preparation, the teeth were obturated, and prefabricated posts were cemented into the prepared spaces. Posts were ultrasonically instrumented dry and with irrigation at 20 mL/min and 40 mL/min. Temperature changes on the entire mesial outer surfaces of the roots were measured at 10-second intervals using an infrared thermal imaging camera.

RESULTS

Increases in root surface temperature were significantly lower when posts were instrumented with 40 mL/min water irrigation compared with dry vibration and 20 mL/min irrigation, which also significantly differed from each other. Statistical analysis among tooth groups showed differences in the mean temperature rise of maxillary central incisors and maxillary lateral incisors compared with mandibular incisors when posts were instrumented dry or with 20 mL/min irrigation. There were no significant differences in mean temperature rises between the studied groups when 40 mL/min irrigation was used.

CONCLUSIONS

Water cooling during ultrasonic post instrumentation significantly reduced temperature increases on the outer root surface; however, the intensity of the cooling was also important. Our results suggest that copious water irrigation during post removal is an effective method to protect the root's surrounding tissue.

Temperature rise during photo-activated disinfection of root canals

The aim of this study was to determine whether it is safe to use photo-activated disinfection (PAD) during root canal treatment without heating the periodontal tissues. Root canals of 30 freshly extracted single-rooted teeth were prepared using ProFiles up to size ISO 40 and then filled with photo-sensitiser: tolonium blue (1.2 mg/l). The 635 nm diode laser was used with the manufacturer's endo-tip. Samples were irradiated for 150 s (output power 100 mW, approximate energy density 106.16 J/cm(2)). Temperatures were recorded at working length on the external root surface. After 150 s of PAD irradiation, the average temperature rise was 0.16 +/- 0.08 degrees C. All values were lower than the 7 degrees C safety level for periodontal injury. It was concluded that, regarding the temperature increase, the use of PAD in root canals could be considered harmless for periodontal tissues.

The Effect of Ultrasonic Post Instrumentation on Root Surface Temperature

This study measured root surface temperature changes when ultrasonic vibration, with and without irrigation, was applied to cemented endodontic posts. Twenty-six, extracted, single-rooted premolars were randomly divided into two groups. Root lengths were standardized, canals instrumented, obturated, and posts cemented into prepared spaces. Thermocouples were positioned at two locations on the proximal root surfaces. Samples were embedded in plaster and brought to 37 degrees C in a water bath. Posts were ultrasonically vibrated for 4 minutes while continuously measuring temperature. Two-way ANOVA compared effects of water coolant and thermocouple location on temperature change. Root surface temperatures were significantly higher (p < 0.001) when posts were instrumented dry. A trend for higher temperatures was observed at coronal thermocouples of nonirrigated teeth and at apical thermocouples of irrigated teeth (p = 0.057). Irrigation during post removal with ultrasonics had a significant impact on the temperature measured at the external root surface.