Scope of Preparation of Oval and Long-Oval Root Canals: A Review of the Literature.

Successful endodontic treatment depends on cleaning and disinfecting the root canals, in order to provide conditions for three-dimensional filling, which should prevent root canal reinfection. However, anatomical complexities pose a challenge during endodontic treatment. The present study was a literature review carried out in the following databases: PubMed, SciELO, and MEDLINE, which were searched for articles published from 2017 to 2021. Micro-CT studies published in English, which analysed the capacity for preparation of oval and long-oval root canals, were included. The following keywords were used: "oval-shaped canals," "long-oval-shaped canals," "endodontics," and "micro-CT." The aim of this study was to carry out a literature review of micro-CT studies on the scope of the capacity for preparation performed in oval and long-oval root canals with rotary and reciprocating instruments.

Do the ball-ended probe cause less damage than sharp explorers?-An ultrastructural analysis.

BACKGROUND: No evidence about damage caused by ball-ended probes on tooth is available. No study compared probing defects caused by ball-ended probes with sharp explorers during tactile examinations of primary teeth. This exploratory study aimed to compare ultrastructural defects caused by ball-ended probes with sharp explorers during tactile examinations of primary teeth. METHODS: Forty-nine primary extracted teeth were tactile examined as performed for caries activity assessment. Surfaces were randomly divided into groups based on probe type (ball-ended probe or sharp explorer). Two examiners probed different surfaces using the sharp explorer and the ball-ended probe. The order for examination was randomly determined. Images were captured using environmental scanning electron microscopy (ESEM) before and after probing. Two external examiners evaluated independently the ESEM images and scored them as: 0) no damage, 1) slight marks, 2) distinct marks, 3) marks with discontinuity, 4) enamel break-offs. Multilevel Poisson regression models were used to analyze associations between probing ultrastructural damage and surface type, baseline condition and probe type. Prevalence ratios (PR) were calculated with 95 % confidence interval (CI). RESULTS: The most common defects observed on the dental surfaces were probing marks without discontinuity (scores 1 and 2). Ball-ended probes caused significantly less severe damage than sharp explorers (PR: 0.28; CI: 0.11-0.76, p = 0.01). CONCLUSION: Ball-ended probes cause less damage than sharp explorers when probing gently dental surfaces of primary teeth.

Preliminary study to establish a relationship between tactile sensation and surface roughness.

This study evaluated the ability of tactile sensations to distinguish roughness. Five examiners experienced in visual examination participated. Tactile sensation was assessed by 3 standard references, the average roughnesses 0.49, 0.92 and 1.54 mum. The examiners evaluated the roughness using 2 different ends of sharp explorers (TU 17 SE and 23 SE), each with 2 different handles (Standard Handle and No. 6 Handle-Satin Steel), and 1 WHO probe using a 5-point response score. The examiners performed 3 evaluations to establish repeatability. Using the 23 SE explorer with the steel handle was the best option to distinguish between 3 roughnesses (p < 0.05). The intraexaminer intraclass correlation coefficients (ICC) were between 0.90 and 0.98, but the interexaminer ICC were only between 0 and 0.04, indicating that, although trained examiners could repeat their own scores, they were not consistent with each other in grading roughness.

Dental devices: classification of dental amalgam, reclassification of dental mercury, designation of special controls for dental amalgam, mercury, and amalgam alloy. Final rule.

The Food and Drug Administration (FDA) is issuing a final rule classifying dental amalgam into class II, reclassifying dental mercury from class I to class II, and designating a special control to support the class II classifications of these two devices, as well as the current class II classification of amalgam alloy. The three devices are now classified in a single regulation. The special control for the devices is a guidance document entitled, "Class II Special Controls Guidance Document: Dental Amalgam, Mercury, and Amalgam Alloy." This action is being taken to establish sufficient regulatory controls to provide reasonable assurance of the safety and effectiveness of these devices. Elsewhere in this issue of the Federal Register, FDA is announcing the availability of the guidance document that will serve as the special control for the devices.

A preliminary survey of impression trays used in the fabrication of fixed indirect restorations.

PURPOSE: A variety of impression trays are used in the fabrication of fixed indirect restorations. Impressions used in the construction of fixed indirect restorations were examined for tray type, manner of use, and overall impression quality. MATERIALS AND METHODS: A commercial dental laboratory provided 1403 impressions used to fabricate fixed indirect restorations during a 3-month period. Impressions were examined for tray type, quantity and type of recorded abutments, the impression of intact teeth adjacent to and opposing the abutment, the presence of the canine in the impression, and an assessment of the quality of the impression. RESULTS: A majority of trays examined were plastic (864, or 61.6%). Dual-arch trays comprised 73.1% of the total. Most of these were metal posterior (n = 499) or plastic posterior (n = 280). Among partial dual-arch impressions, 561 (55.7%) were for the single abutment restoration, bounded by intact teeth anterior and posterior, and with an intact opposing tooth. Eleven percent of plastic dual-arch impressions failed to register the canine. Regarding restoration type, there were 955 impressions for the single-tooth crown, 46 for implant-supported restorations, and 11 for veneers. Twenty impressions were for posts, inlays, or onlays. Impressions for multiple single-tooth crowns and fixed partial dentures comprised the remainder. In terms of overall quality, 85.3% of impressions were excellent or good. The lowest performance in terms of excellent quality was in the anterior plastic single-arch impression (44.8%), whereas the best rate of excellent quality noted was for the posterior dual-arch impression (82.4%). CONCLUSIONS: Within the limitations of this study, dual-arch trays were the most commonly used tray. Recommendations for the use of the dual-arch tray were not followed in a substantial number of impressions examined.

A novel simplified numbering system for dental burs.

A universally accepted standardization is of great value for any material or equipment that is used globally. A single number or name should represent the particular material or instrument throughout the world. Since the dental burs are used worldwide, a single standard numbering system, which gives a unique specification for each bur in any part of the world, is mandatory. Though the existing systems have tried to attain this goal, they have their own advantages and limitations that are explained in detail in this article. So, the idea of proposing a novel system is to formulate a simple way of mentioning each bur with its dimension and composition without the need for memorizing the numbers.

Aspiration and ingestion in dental practice: a 10-year institutional review.

BACKGROUND: This article is an institutional retrospective review of incidents involving aspiration and ingestion of dental foreign objects at a large multidisciplinary dental educational facility. It was undertaken to determine which dental procedures were more likely to involve aspiration or ingestion, as well as to evaluate the outcome of these adverse incidents. METHODS: The inclusion criteria involved all patients who were documented to have experienced loss of dental instruments or material behind the posterior pharynx during a 10-year consecutive period. The dental and medical records of these patients were analyzed, and the outcomes of the adverse events fell into three categories: aspiration, ingestion, or neither aspirated nor ingested. The authors also noted the type of dental instrument and the specialty or area of dentistry in which this event occurred. RESULTS: There were 36 documented cases. Twenty-five of these were instances of ingestion and one was an aspiration. In 10 cases, aspiration and ingestion were ruled out through radiographic examination or the object was retrieved from the patient's mouth. CONCLUSIONS: Fixed prosthodontic therapy had the highest number of incidents of adverse outcomes. Ingestion was a more prevalent outcome than aspiration. Dental procedures involving single-tooth cast or prefabricated restorations involving cementation have a higher likelihood of aspiration. CLINICAL IMPLICATIONS: The implications for clinical practice include the recognition of risk that dental therapy demands in regard to the airway and posterior pharynx, documentation and follow-up of adverse outcomes, and the use of preventive measures such as rubber dams or gauze throat screens or floss ligatures.

[Comparative study of the effects of rotating instruments on the dental surface]. / Studio comparativo sugli effetti degli strumenti rotanti sulla superficie dentale.

This study analyses the relationship between the use of rotating instruments, the production of a smear layer and the presence of alterations to enamel microstructures. The rotating instruments used were carbide (8-12 blade) and diamond tipped (30-15 m) cutters. Cavities were made in extracted teeth. Subsequently, half the sample was analysed using the rugosimeter before and after the application of ortophosphoric acid at 35% for 15 and the other half suing a Scansion Electronic microscope (SEM). The results obtained showed on the one hand that carbide cutters leave a smoother surfacer than diamond tipped cutters, and on the other that the smear layer is eliminated better by carbide cutters compared to diamond tipped cutters. Moreover, there are no major traumatic-type alterations at the level of the enamel affecting the microstructure after the use of carbide cutters.

[Effect of ultrasonic scalers, burs and silicone points on the resins for denture bases]. / Effetto degli ultrasuoni, di frese e di gomme abrasive sulle resine per basi protesiche.

BACKGROUND: Complete dentures in elderly patients often present a large build-up of dental calcolus. In order to avoid this leading to the onset of mycosis or other infections of the oral cavity, all the dental calcolus must be removed during check-ups. METHODS: In order to analyse the consequences of removing the dental calcolus by mechanical means on the resin of the dentures, a polymethylmetacrylate (PMMA) plate was treated with a ultrasonic scaler, with rotating silicone points and with tungsten carbide burrs mounted on a straight hand-grip. The specimens were observed under a light stereomicroscope and their surface was analysed using a surface roughness tester. Observation under the stereomicroscope showed that in all cases the smooth surface of the resin is damaged and modified. RESULTS: The analysis using the surface roughness tester revealed that only very limited quantities of resin are removed whatever the method. Using the lateral edge of the ultrasonic scaler tip and the rotating silicone points mounted on a hand-grip were the techniques that gave the best results, causing the least abrasions. CONCLUSIONS: The results obtained show that after removing the dental calcolus with the instruments tested, the dentures need to be polished in order to prevent the roughness and irregularities caused by the instruments from favouring plaque retention and the consequent reformation of dental calcolus.

[Comparative evaluation of different instruments for root canal preparation tested on extracted human teeth III. Study of sonic and ultrasonic instruments]. / A gyökércsatorna-tágító müszerek összehasonlító értékelése kihúzott emberi fogakon III. rész. A hangfrekvenciás és az ultrahangmüszerek vizsgálata.

A total of 460 roots of extracted human teeth were divided into three groups i.e. straight, apically curved and entirely curved groups. Each of the three groups were divided into seven subgroups according to instrumentation by conventional hand, K-Flex file, 3-LD, 3-LDSY, Excalibur. MM 1400 and Endo Sonic. Radiographs were taken both clinical and proximal views before and after the enlargement of canals. An assessment of shaping characteristic of instrumentation was made on the basis of overimposed radiographs including perforation, ledge formation smoothness of wall contour incidence of elbow and zip measurements at the elbow level and asymmetry measurements. The majority of enlarged root canals were asymmetrical in shape. High differences were found between the incidence of elbow and zip formation. Under laboratory conditions the K-Flex file produced minor canal aberrations and significantly less asymmetry than the conventional instruments. But both the above mentioned instruments caused perforations on curved canals, such as the instrumentation by Excalibur. The loss of working distance was significant in all canal forms prepared with 3-LD and 3-LDSY instruments, which could have occurred through the packing of debris towards the apical constriction. The Excalibur appeared to be superior to the conventional hand instrument in straight canals, but its shaping characteristic was similar to conventional hand instrument in curved canals. The MM 1400 handpiece and ultrasonic instruments resulted in less aberration and significantly less asymmetry than the other tested instruments.

Instrumentación rotatoria en endodoncia. ¿Qué tipo de lima o procedimiento es el más indicado? / Rotary instrumentation in endodontics: which kind of lime you might use

El objetivo del presente trabajo es realizar una revisión bibliográfica de los últimos diez años a cerca de la instrumentación rotatoria en endodoncia y de los diferentes tipos de limas que se pueden usar, buscando una comparativa de ventajas y desventajas e incluso posibles indicaciones para cada caso y tipo de lima o procedimiento. EL sistema de endodoncia rotatoria ha significado un avance extraordinario en el tratamiento de conductos tanto de dientes anteriores como posteriores. La instrumentación rotatoria permite utilizando un menor número de limas, darle una mayor conicidad que facilite la limpieza del conducto y su posterior obturación. Por ello se pretende explicar la técnica de instrumentación mecánica de los conductos radiculares, exponiendo su diseño, características de composición, forma de uso y las ventajas o inconvenientes respecto a otros sistemas (AU)

The objective of the present work is to perform a literature review of the last ten years about rotary instrumentation in endodontics and the different types of files that can be used, searching for a comparative of advantages and disadvantages and even possible indications for each case. File type or procedure. The rotational endodontic system has meant an extraordinary advance in the treatment of ducts of both anterior and posterior teeth. The rotary instrumentation allows using a smaller number of files, give a greater conicity that facilitates the cleaning of the duct and its subsequent obturation. The aim of this work is to explain the technique of mechanical instrumentation of the root canal, exposing its design, characteristics of composition, form of use and the advantages or disadvantages with respect to other systems (AU)

Durabilidad de las fresas de diamante tras realizar desgastes en dientes naturales, comparando 4 marcas comerciales, analizado en microscopía electrónica / Diomond Burs durability, aer tooth wears, 4 brands compaired. Electronic Microscopy analysis

Antecedentes: Los hallazgos reportados en la literatura no relacionan directamente la efectividad de corte de las fresas de diamante de alta velocidad con la cantidad y calidad de diamantes en la superficie, ni su vida media después de un determinado número de usos. Objetivo: Evaluar la durabilidad de los diamantes de corte de la superficie activa de las fresas después de realizar desgastes en dientes naturales. Métodos: Este estudio ex vivo comparó 4 marcas comerciales de fresas de diamante con granos de 64-126 |zm, de forma troncocónica y punta redonda (norma ISO 850): MDT", Swisstech*, Pointech* y Jota". Se realizaron 5 cortes de 0,16 mm con cada fresa en la corona del diente. Luego se analizaron las fresas en microscopio electrónico de barrido para observar: a) adhesión de diamantes al sustrato en cabeza y cuerpo; b) estado de los diamantes en el sustrato en cabeza y cuerpo, tras los 5 cortes; y c) estadofinal de las fresas. Se realizó un análisis cualitativo y cuantitativo. Resultados: Todas las fresas de las 4 marcas presentaron similar desgaste después de los 5 usos, tanto en la cabeza como el cuerpo. Pese a que todas las muestras presentaban variaciones, en algunas fue más evidente el desalojo y fractura de los diamantes. Conclusión: El estudio sugiere que las fresas deberían cambiarse después de 5 usos clínicos para garantizar un desgaste adecuado y evitar daños pulpares ocasionados por la fricción.

Background: Outcomes reported in the literature do not relate cutting effectiveness of high-speed diamond drills directly to the diamond surface amount and quality, not either their average life after a specific number of uses. Objective: To evaluate the durability of diamond burrs in the drill active surface after doing removal in natural teeth. Methods: This ex vivo study compared dental drills of four different brand names with 64-126 pm, round tip, conical-trunk diamond grit (ISO 850): MDT", Swisstech", Pointech* and Jota". Five 0.16 mm cuts were carried out using each dental drill on a tooth crown. The dental drills were then analyzed under the scanning electron microscope in order to observe: a) any adhesion of diamond to substrate in the head and body; b) condition of the diamonds in the substrate, in head and body, after 5 cuts; and c) final condition of the dental drills. Then a qualitative and quantitative analysis was carried out. ResuJts: The four different dental drills showed a similar worn condition after five uses, both in the head and body. Despite all the samples showed variations, some of them had greater evidence of diamond fracture and displacement. Conclusion: This study suggests that the dental drills should be changed over after 5 clinical uses in order to ensure a desirable worn condition and prevent pulpal damage due to the friction.

Shaping canals with ProFiles and K3 instruments: does operator experience matter?

OBJECTIVE: The aim of this study was to determine the influence of operator experience on the shaping ability of ProFile and K3 nickel-titanium rotary instruments in simulated root canals. STUDY DESIGN: One hundred sixty simulated canals consisting of 4 different shapes in terms of angle and position of curvature were prepared by experienced and inexperienced operators. One experienced operator prepared 80 canals and 2 inexperienced operators prepared 80 canals with a crown-down technique using either ProFile or K3 .06 taper instruments. Images of the canals were taken, using a camera attached to a computer with image analysis software, before surgery and after preparation to sizes 20, 25, and 30 to working length. Postoperative images were combined with the preoperative image to highlight the amount and position of material removed during preparation as well as the shape of the prepared canal. RESULTS: Overall, there was a highly statistically significant difference (P<.001) between the instruments for the time taken to prepare the canals, with K3 instruments taking a mean of 4.9 minutes and ProFile 6.0 minutes. Six instruments fractured (3 in each operator category); 4 were ProFile instruments. Four instruments deformed, all with the inexperienced operators; 3 were K3. No perforations or zips were observed; however, 1 danger zone (created by the experienced operator using K3 instruments) and 1 ledge (created by an inexperienced operator using K3 instruments) were created. Twelve outer widenings were created with a highly significant difference (P<.001) between the operator and instrument used. There was a highly significant difference by instrument (P<.001), and experience (P=.008) regarding absolute transportation at the beginning of the curve and a statistically significant difference (P=.031) for the instrument used regarding absolute transportation half way to the orifice. CONCLUSION: The experienced operator prepared canals more quickly and safely than the inexperienced operators when using K3 instruments; both used ProFile instruments quickly and safely. Inexperienced operators would be advised to train using less aggressive instruments and when confident could progress to other instrument designs.